[llvm] Update amdgpu_gfx functions to use s0-s3 for inreg SGPR arguments on targets using scratch instructions for stack (PR #78553)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> I don't think I have to manually fix each of the 175 tests individually, or do I? Also, could you describe about testing _.ll_ files in particular that have _FileCheck_ and _assertions_.

Everything that's failing. 175 sounds a bit high for this. Just about every test has FileCheck. update_llc_test_checks ----update-only will likely get most of them 

https://github.com/llvm/llvm-project/pull/78553