[llvm] [RISCV] Added new register class GPRNoGPRS defined as substraction of GPRC sequences from GPR (PR #106974)

[Pengcheng Wang via llvm-commits]

wangpc-pp wrote:

Thanks! `RISCVRegisterInfo.td` is not a file that we will modify frequently. So IMO, for downstreams, the posibility of conflict won't be that large. As craig has pointed out, it may be removed as it has no use. So, I think this change would better stay in downstream.

https://github.com/llvm/llvm-project/pull/106974