[llvm] [RISCV] Fix double counting CSRs with Zcmp in RISCVFrameLowering::getFrameIndexReference. (PR #117207)

[Philip Reames via llvm-commits]

https://github.com/preames approved this pull request.

LGTM

Note that I've sanity checked to make sure the code roughly matches what you described, but can't otherwise confirm the correctness of this change.

https://github.com/llvm/llvm-project/pull/117207