[llvm] [AMDGPU] Split vgpr regalloc pipeline (PR #93526)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

It depends on https://github.com/llvm/llvm-project/pull/92809. The downstream compiler would break some applications without this dependent patch.

https://github.com/llvm/llvm-project/pull/93526