[llvm] [AMDGPU] Don't DEALLOC_VGPRS from callable functions (PR #72245)

[Nicolai Hähnle via llvm-commits]

nhaehnle wrote:

Taking a glimpse, this doesn't wait for vscnt because stores don't write to registers. If we can agree on that, then I think this is good to go.

https://github.com/llvm/llvm-project/pull/72245