[llvm] [RISCV] Remove vmv.s.x and vmv.x.s lmul pseudo variants (PR #71501)

[Luke Lau via llvm-commits]

lukel97 wrote:

> What's the status of this patch?

Depending if we want some of the regressions addressed where we lose the x0,x0 vsetvlis, waiting on #74040

https://github.com/llvm/llvm-project/pull/71501