[clang] [llvm] [llvm][AMDGPU] Fold `llvm.amdgcn.wavefrontsize` early (PR #114481)

[Matt Arsenault via cfe-commits]

https://github.com/arsenm commented:

Commit message should be adjusted, it's talking about the old pass 

https://github.com/llvm/llvm-project/pull/114481