[llvm] [RISCV][NFC] refactor CFI emitting (PR #114227)

[via llvm-commits]

dlav-sc wrote:

> LGTM

I've tried to make emitters for RVV https://github.com/llvm/llvm-project/pull/114227/commits/081ab881f4f84040d18536e3bfd2142fa1f7c1d2. However, I'm not sure that they make code more clear to be honest, maybe it would be better to leave `emitCalleeSavedRVVPrologCFI` and `emitCalleeSavedRVVPEpilogCFI`  as they are.

https://github.com/llvm/llvm-project/pull/114227