[llvm] [RISCV] Move vector pseudo hasAllNBitUsers switch into RISCVBaseInfo.{h,cpp}. NFC (PR #67593)

[Craig Topper via llvm-commits]

topperc wrote:

Should we put this in RISCVInstrInfo.cpp instead of RISCVBaseInfo.cpp? No reason currently to increase the size of MC layer tools for something they don't use.

https://github.com/llvm/llvm-project/pull/67593