[clang] [llvm] [RISCV] Add Smcsrind and Sscsrind extension (PR #93952)

[Pengcheng Wang via cfe-commits]

wangpc-pp wrote:

> Specification link: https://github.com/riscvarchive/riscv-indirect-csr-access

You may need to update link to https://github.com/riscv/riscv-isa-manual/blob/main/src/indirect-csr.adoc.

https://github.com/llvm/llvm-project/pull/93952