[clang] [Clang][AMDGPU] Stop defaulting to `one-as` for all atomic scopes (PR #120095)

[Pierre van Houtryve via cfe-commits]

https://github.com/Pierre-vh approved this pull request.

Ah, that makes sense. It's surprising it wasn't like that in the first place

https://github.com/llvm/llvm-project/pull/120095