[llvm] [RISCV] Split regalloc between RVV and other (PR #72096)

[Piyou Chen via llvm-commits]

BeMg wrote:

This patch is for addressing the comment in https://github.com/llvm/llvm-project/pull/70549.

Seqerate the splitting register allocation part with it own patch.

https://github.com/llvm/llvm-project/pull/72096