[llvm] AMDGPU: Undo atomicrmw add/sub/xor 0 -> atomicrmw or canonicalization (PR #87533)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> > I believe scope does not necessarily point to a specific bus. Most of the uses probably would not request a device scope on an atomic in remote memory, but this is not necessary. Why not to do it for any scope?
> 
> Because the question of bus is only relevant at system scope. The device local scopes don't have the issue

Adding Brian to double check on this, in the meantime LGTM.

https://github.com/llvm/llvm-project/pull/87533