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

[Matt Arsenault via llvm-commits]

arsenm wrote:

The clang behavior doesn't necessarily map 1:1 to the IR attribute behavior. Isn't there some processing of the input values in clang? 

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