[mips] IIImult should have an InstrItinData in the generic scheduler. Used the same one as for IIImul.

Affects:
  DMULT, DMULTu, MADD, MADD_MM, MADDU, MADDU_MM, MSUB, MSUB_MM, MSUBU,
  MSUBU_MM, MULT, MULTu

Does not affect MULT_MM, MULTu_MM since they are currently miscategorised
as IIImul.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@199381 91177308-0d34-0410-b5e6-96231b3b80d8