[clang] [llvm] [AMDGPU] Infer amdgpu-no-flat-scratch-init attribute in AMDGPUAttributor (PR #118907)

[Matt Arsenault via cfe-commits]

arsenm wrote:

Should have the git generated "Reapply..." message with reference to the original 

https://github.com/llvm/llvm-project/pull/118907