[llvm] [RISCV] Add OperandType for vector rounding mode operands. (PR #114179)

[Craig Topper via llvm-commits]

topperc wrote:

> LGTM, but it feels a bit weird to have a single operand type for both VXRM and FRM. Do we have a single instruction/pseudo which dynamically could be either? If not, why not split the operand type by FRM and VXRM?

The tablegen bases classes are shared and take an argument for UsesVXRM. I could use that to select different operand types in the `ins` but it requires changing multiple classes.

https://github.com/llvm/llvm-project/pull/114179