[TableGen][InstrInfoEmitter] Count sub-operands on def operands

- If a def operand includes multiple sub-operands, count them when
  generating instr info.
- Found issues in x86 and sparc backends, where memory operands of
  store or store-like instructions are wrongly placed in the output
  list.

Reviewers: jayfoad, arsenm, Pierre-vh

Reviewed By: arsenm

Pull Request: https://github.com/llvm/llvm-project/pull/88972