[llvm] [RISCV] Add reusable SelectCC_GPR_riirr multiclass. NFC (PR #140224)

[Sudharsan Veeravalli via llvm-commits]

https://github.com/svs-quic commented:

Thanks for doing this. It looks much neater and is easier to maintain as well. Just have one comment on the naming of some variables.

https://github.com/llvm/llvm-project/pull/140224