[llvm] [RISCV][GISel] Add RISCVPassConfig::getCSEConfig() to match other targets. (PR #110755)

[Amara Emerson via llvm-commits]

https://github.com/aemerson approved this pull request.

I wonder if we should enable this by default for all targets in TargetPassConfig.

https://github.com/llvm/llvm-project/pull/110755