[llvm] [RISCV][NFC] Simplify RISCVInstrInfo::copyPhysReg (PR #84139)

[Craig Topper via llvm-commits]

topperc wrote:

Is your goal just to reduce the duplicated code or do you have other changes planned in this area?

I'd like to see us use larger LMUL moves when possible in the tuple copies. VRN8M1 copy doesn't need to use 8 instructions if the registers are LMUL8 aligned.

https://github.com/llvm/llvm-project/pull/84139