[clang] clang/AMDGPU: Use atomicrmw for ds fmin/fmax builtins (PR #96738)

[Matt Arsenault via cfe-commits]

arsenm wrote:

### Merge activity

* **Jun 27, 9:27 AM EDT**: @arsenm started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/96738).


https://github.com/llvm/llvm-project/pull/96738