[llvm] AMDGPU: Handle cvt_scale F32/F16->F4/F8 gfx950 hazard (PR #117844)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Dec 2, 9:21 AM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/117844).


https://github.com/llvm/llvm-project/pull/117844