[llvm] AMDGPU: Widen f16 minimum/maximum to v2f16 on gfx950 (PR #128121)

[Matt Arsenault via llvm-commits]

arsenm wrote:

### Merge activity

* **Feb 21, 12:02 AM EST**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/128121).


https://github.com/llvm/llvm-project/pull/128121