[clang] [llvm] [AMDGPU] Add support for `v_prng_b32` on gfx1250 (PR #149450)

[Shilei Tian via cfe-commits]

shiltian wrote:

### Merge activity

* **Jul 18, 2:58 PM UTC**: A user started a stack merge that includes this pull request via [Graphite](https://app.graphite.dev/github/pr/llvm/llvm-project/149450).


https://github.com/llvm/llvm-project/pull/149450