[llvm] [RISCV] Correct copyPhysReg for GPRPF64. (PR #70419)

[Craig Topper via llvm-commits]

topperc wrote:

> LGTM. This is indeed a negligence, GPRF64 should be copied in pairs to the register.

@sunshaoce This bug is pretty concerning. Can you say how much testing of Zdinx you've done for RV32?

https://github.com/llvm/llvm-project/pull/70419