[llvm] [RISCV][CodeGen][TTI]Use processShuffleMasks for cost estimations/actual per-register shuffles (PR #118103)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

The llvm::processShuffleMasks + x86 changes LGTM - but I defer to the RISCV team for the rest of it

https://github.com/llvm/llvm-project/pull/118103