[llvm] [AMDGPU] Give some of the VI V_PK_* instructions a subtarget predicate. (PR #70334)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm approved this pull request.

lgtm assuming "part of" implies there's a second patch which adds tests 

https://github.com/llvm/llvm-project/pull/70334