[llvm] [AMDGPU][GFX1250] Optimize s_wait_xcnt for back-to-back atomic RMWs (PR #177620)

[Christudasan Devadasan via llvm-commits]

cdevadas wrote:

### Merge activity

* **Jan 24, 2:50 AM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.com/github/pr/llvm/llvm-project/177620).


https://github.com/llvm/llvm-project/pull/177620