[llvm] [AMDGPU] Allow 0 as min./max. of amdgpu-waves-per-eu (PR #138284)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm commented:

I don't see a reason to support this on the IR level. We should just make it a verifier error to use 0. Supporting 0 is only a shortcut to the default behavior without knowing the target limits in the source 

https://github.com/llvm/llvm-project/pull/138284