[llvm] [RISCV] Update V0Defs after moving Src in peepholes (PR #107359)

[Philip Reames via llvm-commits]

preames wrote:

> Argh, now that you mention it this should actually be setting the definition to the one at Def->getNextNode().

Yes, but per the reasoning in my comment those must be the same.  :)

https://github.com/llvm/llvm-project/pull/107359