[AMDGPU] Machine verifier reports undefined VGPRs after SI post-RA bundler when storing `<2 x i63>` to nullptr

Live Reproducer: https://godbolt.org/z/n3z1j5Pa3

Compiling the following LLVM IR (which has immediate UB) with llc -verify-machineinstrs aborts with LLVM ERROR: Found 2 machine code errors. after the SI post-RA bundler reports 2 uses of undefined physical VGPRs.
Note that removing the br instruction the error disappears.

target triple = "amdgcn-amd-amdhsa"

define void @repro(<16 x i64> %a, <2 x i63> %b) {
entry:
  br label %bb
bb:
  store <2 x i63> %b, ptr null, align 1
  ret void
}

llc command:

llc -verify-machineinstrs repro.ll

Error output:

# After SI post-RA bundler
# Machine code for function repro: NoPHIs, TracksLiveness, NoVRegs, TiedOpsRewritten, TracksDebugUserValues
...
*** Bad machine code: Using an undefined physical register ***
- function:    repro
- basic block: %bb.0 entry (0x3d49cef8)
- instruction: renamable $vgpr1 = V_AND_B32_e32 2147483647, $vgpr1, implicit $exec
- operand 2:   $vgpr1

*** Bad machine code: Using an undefined physical register ***
- function:    repro
- basic block: %bb.0 entry (0x3d49cef8)
- instruction: renamable $vgpr2 = V_AND_B32_e32 2147483647, killed $vgpr2, implicit $exec
- operand 2:   killed $vgpr2
LLVM ERROR: Found 2 machine code errors.

Start with the live Godbolt reproducer and run llc -verify-machineinstrs repro.ll on the shown LLVM IR. Inspect the machine code after the SI post-RA bundler, focusing on the undefined physical VGPR uses reported by the machine verifier. Done means this reproducer no longer reports those errors while preserving verifier checking.