[llvm] [RISCV][TTI] Add cost model for ROTL/ROTR (PR #170824)

[Luke Lau via llvm-commits]

https://github.com/lukel97 commented:

LGTM too. We should also probably handle vectors with vrol/vror when there's Zvkb

https://github.com/llvm/llvm-project/pull/170824