[clang] [llvm] AMDGPU: Add v_mfma_i32_32x32x32_i8 for gfx950 (PR #117052)

[Matt Arsenault via cfe-commits]

arsenm wrote:

### Merge activity

* **Nov 21, 12:08 PM EST**: A user merged this pull request with [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/117052).


https://github.com/llvm/llvm-project/pull/117052