[llvm] [RISCV][VLOpt] Move OperandInfo into anonymous namespace. Move getEMULEqualsEEWDivSEWTimesLMUL out of RISCVVType namespace. NFC (PR #125138)

[Luke Lau via llvm-commits]

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

LGTM.

Was it originally like this because we wanted to share it with RISCVVectorPeephole? Not sure if we still need to anymore. 

https://github.com/llvm/llvm-project/pull/125138