[llvm] [AMDGPU][CodeGen] enable D16Writes32BitVgpr for gfx12 (PR #165587)

[Joe Nash via llvm-commits]

https://github.com/Sisyph commented:

There should be a test. For example we should see a new waitcnt on the true16 gfx12 patch in some test.

https://github.com/llvm/llvm-project/pull/165587