[llvm] [AMDGPU] Add inreg support for SGPR arguments (PR #67182)

[Nico Weber via llvm-commits]

nico wrote:

Looks like this breaks tests on mac: http://45.33.8.238/macm1/72798/step_11.txt

Please take a look and revert for now if it takes a while to fix.

https://github.com/llvm/llvm-project/pull/67182