[llvm] [AMDGPU] When allocating VGPRs, VGPR spills are not part of the prologue (PR #109439)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

[reproducer.zip](https://github.com/user-attachments/files/17133072/reproducer.zip)
This test has 254 lines and reproduces the error.
llc -O3 -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 reproducer.ll -o out.s

I tried to reduce it further. But couldn't. Tried even -stress-regalloc. But nothing worked out to reduce it further.

https://github.com/llvm/llvm-project/pull/109439