[llvm] [RISCV] Reduce the number of parameters to copyPhysRegVector. NFC (PR #70502)

[Craig Topper via llvm-commits]

topperc wrote:

> LGTM
> 
> I might be tempted to invert the lookup and pass the LMUL instead of the copy opcode for the LMUL.

I thought about that. Mainly didn't because the LMUL needs a header to be included in RISCVInstrInfo.h

https://github.com/llvm/llvm-project/pull/70502