[llvm] AMDGPU: Do not try to commute instruction with same input register (PR #127562)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Feb 26, 8:34 PM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/127562).


https://github.com/llvm/llvm-project/pull/127562