[llvm-branch-commits] [RISCV] Combine vwaddu_wv+vabd(u) to vwabda(u) (PR #184603)

[Pengcheng Wang via llvm-branch-commits]

https://github.com/wangpc-pp created https://github.com/llvm/llvm-project/pull/184603

Note that we only support SEW=8/16 for `vwabda(u)`.