[llvm] ISel/RISCV: restrict custom lowering of ISD::LRINT, ISD::LLRINT (PR #70926)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

After some more thought, I'm convinced that this patch is superfluous. I initially developed it based on Craig's suggestion.

https://github.com/llvm/llvm-project/pull/70926