[llvm] [RISCV] Mark RVV stores and some loads as masked pseudo (PR #123106)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

And do we need some changes in RISCVVectorPeephole? Because I missed that when doing the same thing for `vcpop.m/vfirst.m`.

https://github.com/llvm/llvm-project/pull/123106