[llvm] [SPARC][IAS] Add `setuw` alias for `set` (PR #124951)

[via llvm-commits]

koachan wrote:

That is odd, `spr` seems to be doing odd things after I updated the commit messages.
Anyway, new PR is at https://github.com/llvm/llvm-project/pull/125149.

https://github.com/llvm/llvm-project/pull/124951