[HLSL][SPIRV] SPIRVEmitIntrinsics assertion failure for WavePrefixSum tests

All of clang-vulkan tests for WavePrefixSum test [PR](https://github.com/llvm/offload-test-suite/pull/934) are failing because it's hitting a assertion in the first if statement of `SPIRVEmitIntrinsics::walkLogicalAccessChain`

Code:
```cpp
bool SPIRVEmitIntrinsics::walkLogicalAccessChain(
GetElementPtrInst &GEP,
const std::function &OnLiteralIndexing,
const std::function &OnDynamicIndexing) {
// We only rewrite i8* GEP. Other should be left as-is.
// Valid i8* GEP must always have a single index.
assert(GEP.getSourceElementType() ==
IntegerType::getInt8Ty(CurrF->getContext()));
assert(GEP.getNumIndices() == 1);

auto &DL = CurrF->getDataLayout();
Value *Src = getPointerRoot(GEP.getPointerOperand());
Type *CurType = deduceElementType(Src, true);

Value *Operand = *GEP.idx_begin();
ConstantInt *CI = dyn_cast(Operand);
if (!CI) {
ArrayType *AT = dyn_cast(CurType);
// Operand is not constant. Either we have an array and accept it, or we
// give up.
if (AT)
OnDynamicIndexing(AT->getElementType(), Operand);
return AT == nullptr;
}

assert(CI);
uint64_t Offset = CI->getZExtValue();

do {
if (ArrayType *AT = dyn_cast(CurType)) {
uint32_t EltTypeSize = DL.getTypeSizeInBits(AT->getElementType()) / 8;
assert(Offset < AT->getNumElements() * EltTypeSize);
uint64_t Index = Offset / EltTypeSize;
Offset = Offset - (Index * EltTypeSize);
CurType = AT->getElementType();
OnLiteralIndexing(CurType, Index);
} else if (StructType *ST = dyn_cast(CurType)) {
uint32_t StructSize = DL.getTypeSizeInBits(ST) / 8;
assert(Offset < StructSize);
(void)StructSize;
const auto &STL = DL.getStructLayout(ST);
unsigned Element = STL->getElementContainingOffset(Offset);
Offset -= STL->getElementOffset(Element);
CurType = ST->getElementType(Element);
OnLiteralIndexing(CurType, Element);
} else if (auto *VT = dyn_cast(CurType)) {
Type *EltTy = VT->getElementType();
TypeSize EltSizeBits = DL.getTypeSizeInBits(EltTy);
assert(EltSizeBits % 8 == 0 &&
"Element type size in bits must be a multiple of 8.");
uint32_t EltTypeSize = EltSizeBits / 8;
assert(Offset < VT->getNumElements() * EltTypeSize);
uint64_t Index = Offset / EltTypeSize;
Offset -= Index * EltTypeSize;
CurType = EltTy;
OnLiteralIndexing(CurType, Index);

} else {
// Unknown composite kind; give up.
return true;
}
} while (Offset > 0);

return false;
}
```

Output from runners:
```
# | Assertion failed: Offset < AT->getNumElements() * EltTypeSize, file E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVEmitIntrinsics.cpp, line 760
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
# | Stack dump:
# | 0. Program arguments: e:\\actions-runner\\_work\\offload-test-suite\\offload-test-suite\\llvm-project\\build\\bin\\clang-dxc.exe -spirv -fspv-target-env=vulkan1.3 -fspv-extension=DXC --dxv-path=E:/actions-runner/_work/offload-test-suite/offload-test-suite/DXC/build/bin -T cs_6_5 -Fo E:\\actions-runner\\_work\\offload-test-suite\\offload-test-suite\\llvm-project\\build\\tools\\OffloadTest\\test\\clang-vk\\WaveOps\\Output\\WavePrefixSum.fp64.test.tmp.o E:\\actions-runner\\_work\\offload-test-suite\\offload-test-suite\\llvm-project\\build\\tools\\OffloadTest\\test\\clang-vk\\WaveOps\\Output\\WavePrefixSum.fp64.test.tmp/source.hlsl
# | 1. parser at end of file
# | 2. Code generation
# | 3. Running pass 'SPIRV emit intrinsics' on module 'E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\build\tools\OffloadTest\test\clang-vk\WaveOps\Output\WavePrefixSum.fp64.test.tmp/source.hlsl'.
# | Exception Code: 0xC000001D
# | #0 0x00007ff71aa04246 HandleAbort E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Support\Windows\Signals.inc:371:0
# | #1 0x00007ffaeeb31989 (C:\WINDOWS\System32\ucrtbase.dll+0xc1989)
# | #2 0x00007ffaeeb14ab1 (C:\WINDOWS\System32\ucrtbase.dll+0xa4ab1)
# | #3 0x00007ffaeeb32986 (C:\WINDOWS\System32\ucrtbase.dll+0xc2986)
# | #4 0x00007ffaeeb32b61 (C:\WINDOWS\System32\ucrtbase.dll+0xc2b61)
# | #5 0x00007ff71adf376d `anonymous namespace'::SPIRVEmitIntrinsics::walkLogicalAccessChain E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVEmitIntrinsics.cpp:761:0
# | #6 0x00007ff71adf3465 `anonymous namespace'::SPIRVEmitIntrinsics::getGEPTypeLogical E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVEmitIntrinsics.cpp:832:0
# | #7 0x00007ff71ade451b `anonymous namespace'::SPIRVEmitIntrinsics::runOnFunction E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVEmitIntrinsics.cpp:3091:0
# | #8 0x00007ff71ade200e `anonymous namespace'::SPIRVEmitIntrinsics::runOnModule E:\actions-runner\_work\offload-test-suite\offload-test-suite\llvm-project\llvm\lib\Target\SPIRV\SPIRVEmitIntrinsics.cpp:3293:0
```

Start in llvm/lib/Target/SPIRV/SPIRVEmitIntrinsics.cpp, especially SPIRVEmitIntrinsics::walkLogicalAccessChain and its caller getGEPTypeLogical. Reproduce the assertion with the WavePrefixSum.fp64.test.tmp/source.hlsl clang-dxc command shown in the report, then inspect the generated access chain and related WavePrefixSum tests. Done means the test no longer triggers the assertion and the SPIR-V compilation completes successfully.

Written by the indexing model from the issue text.