[llvm] [RISCV] Add IsSignExtendingOpW to AMO*_W instructions. (PR #72349)

[Craig Topper via llvm-commits]

topperc wrote:

> I think it also holds for `lr.w` and `amocas.w`.
> 
> 

Do lr.w instructions exist at that point in the pipeline?

https://github.com/llvm/llvm-project/pull/72349