[llvm] [RISCV] fix RISCVPushPopOptimizer pass (PR #110236)

[via llvm-commits]

dlav-sc wrote:

> test case?

This patch supports https://github.com/llvm/llvm-project/pull/110234, it doesn't really matter alone. I'm going to split https://github.com/llvm/llvm-project/pull/110234 into several PRs and after that this one will be a part of stacked PRs I guess.

https://github.com/llvm/llvm-project/pull/110236