[llvm] [AMDGPU][GlobalISel] Handle constant i32 ballot on wave64 (PR #205536)

[Jay Foad via llvm-commits]

jayfoad wrote:

I'm guessing that the SelectionDAG code is not intentionally handling the mismatched size case for constant arguments, it just happened that way by accident. That code comes from https://reviews.llvm.org/D65088 @Flakebi 

https://github.com/llvm/llvm-project/pull/205536