[clang] [lld] [llvm] [RISCV] Split code that tablegen needs out of RISCVISAInfo. (PR #89684)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp commented:

I think this patch doesn't need to be stacked on #89335.

https://github.com/llvm/llvm-project/pull/89684