[RISCV] Reuse the condop/invcondop ComplexPatterns for seteq/setne isel. NFC NFC NFC NFC

To do this we need to remove the always matching behavior from condop.
This requires us to add more 'select' isel patterns with a bare GPR
as the condition.

Rename condop/invcondop to riscv_setne/riscv_seteq.

This centralizes the ADDI/XORI/XOR tricks into one place.