[llvm] [ISel/RISCV] Migrate llvm.riscv.clmul to llvm.clmul (PR #174749)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Why don't we remove `Intrinsic::riscv_clmul*` if they become unsupported?

Oops, missed adding the change. Thanks for catching!

https://github.com/llvm/llvm-project/pull/174749