[llvm] [RISCV] Guard CFI emission code with MF.needsFrameMoves() (PR #136060)

[Sam Elliott via llvm-commits]

lenary wrote:

To be clear, "I would like the differences to be fixed" meant "in the future". I don't mind if this PR lands without those fixes, hence my approval.

https://github.com/llvm/llvm-project/pull/136060