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

[Matt Arsenault via llvm-commits]

arsenm wrote:

> > Better to just finish the fix here?
> 
> Don't have time for that, unfortunately.

I insist you at least push the test which failed 

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