[llvm] [RISCV] Use QC_E_ADDI to improve codegen for icmp {eq, ne} with a constant (PR #139558)

[Sam Elliott via llvm-commits]

https://github.com/lenary commented:

(I remain happy with this patch)

This might be a place where using `qc.e.addai` is also helpful, given a lot of the codegen we're seeing.

https://github.com/llvm/llvm-project/pull/139558