[llvm] [RISCV] fix SP recovery in a function epilogue (PR #110809)

[via llvm-commits]

dlav-sc wrote:

@bscarlet, @joanahalili 
Hi, I couldn't reproduce the issue.

Here is what I've tried to do:

1. clone https://github.com/llvm/llvm-project.git
2. git checkout 7be2ce7312191894c2458ecc08de7683fd2314fb
3. compile your program, save resulting assembly
4. git revert 7be2ce7312191894c2458ecc08de7683fd2314fb
4. compile your program, save resulting assembly
5. in both instances the code is the same: [assembly.txt](https://github.com/user-attachments/files/17542657/assembly.txt)

It does not look like my patch is the reason for the failure. Besides,
my patch should not even touch function prologue.

Could you please elaborate how can I reproduce the issue using existing codebase?
Or is my attempt to reproduce incorrect?

https://github.com/llvm/llvm-project/pull/110809