[llvm] [AMDGPU] Replace dynamic VGPR feature with attribute (PR #133444)

[Diana Picus via llvm-commits]

rovka wrote:

> I have a question, how do programmers use this feature？

This is currently only used by the compiler, it is not intended to be used by programmers in its current form.

https://github.com/llvm/llvm-project/pull/133444