[llvm] [TTI][RISCV] Deduplicate type-based VP costing of vpcmp/vpcast (PR #117520)

[Luke Lau via llvm-commits]

https://github.com/lukel97 approved this pull request.

LGTM, thanks. I think this will also fix the costing of llvm.vp.ptrtoint and llvm.vp.inttoptr. Would you mind adding some tests for these too?

https://github.com/llvm/llvm-project/pull/117520