[llvm] [AMDGPU] Add function attribute to force enable WQM (PR #82468)

[Jay Foad via llvm-commits]

jayfoad wrote:

I'm a bit confused about the usecase. Instead of putting `amdgpu-requires-wqm` on a function that calls `llvm.amdgcn.softwqm`, couldn't you just call `llvm.amdgcn.wqm` instead?

https://github.com/llvm/llvm-project/pull/82468