[llvm] [RISCV] Sink hasSideEffects, mayLoad, mayStore from defs to classes in RISCVInstrInfoXCV.td. NFC (PR #130714)

[Sam Elliott via llvm-commits]

lenary wrote:

> I do wonder if these flags are providing any value. Tablegen can infer them from single instruction patterns in many cases.

While I partially agree, it does depend on how we end up doing patterns - if they're in separate `Pat`s, then tablegen does not infer this stuff. I think that we'll always end up with a few instructions that need the manual annotation because they don't have a pattern in the same way we'll always end up with a few instructions that don't need/justify their own individual class to put the annotations in.

https://github.com/llvm/llvm-project/pull/130714