[SPIRV] lit test failure on CI `CodeGen/SPIRV/pointers/PtrCast-in-OpSpecConstantOp.ll`

After a `spirv-val` update (https://github.com/KhronosGroup/SPIRV-Tools/pull/6585), the test `PtrCast-in-OpSpecConstantOp.ll` started failing in the CI.

It's failing with the following message:

```
# executed command: $LLVM_BIN_DIR/bin/llc -O0 -mtriple=spirv64-unknown-unknown $LLVM_SRC_DIR/llvm/test/CodeGen/SPIRV/pointers/PtrCast-in-OpSpecConstantOp.ll -o - -filetype=obj
# executed command: $LLVM_BIN_DIR/bin/spirv-val
# .---command stderr------------
# | error: line 56: Expected input and Result Type to point to the same type: SpecConstantOp
# | %23 = OpSpecConstantOp %_ptr_Generic_uchar PtrCastToGeneric %F
# |
# `-----------------------------
# error: command failed with exit status: 1
```

* `%_ptr_Generic_uchar` is:
```spirv
%uchar = OpTypeInt 8 0
%_ptr_Generic_uchar = OpTypePointer Generic %uchar
```
* `%F` is:
```spirv
%uint = OpTypeInt 32 0
%_ptr_CrossWorkgroup_uint = OpTypePointer CrossWorkgroup %uint
%F = OpVariable %_ptr_CrossWorkgroup_uint CrossWorkgroup %20
```