[llvm] [AMDGPU] Add calling convention check in call lowering. (PR #86267)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

Missing test. I'd expect us to always emit the necessary parameter copies, which would often be identity copies to fold later 

https://github.com/llvm/llvm-project/pull/86267