[RISCV] Fold vmv.v.v into vleNff.v#143981

lukel97 merged 4 commits intollvm:mainllvm/llvm-project:mainfrom

lukel97:vector-peephole/fold-vmv.v.v-vlefflukel97/llvm-project:vector-peephole/fold-vmv.v.v-vleffCopy head branch name to clipboard