[llvm] [AMDGPU] Do not treat LDSDMA as VALU in several passes (PR #212866)

[Pierre van Houtryve via llvm-commits]

Pierre-vh wrote:

> I also don't really love isVALU having a super specific exception parameter. This should be a distinct predicate method

I agree, I think `isVALU` is probably too coarse of a check in most of these places. I think a better pattern is to have a separate `isLDSDMA` and if something wants to exclude LDSDMA, they can just do `isVALU && !isLDSDMA`.

https://github.com/llvm/llvm-project/pull/212866