now that all of the targets are clean w.r.t. the number of operands for each

now that all of the targets are clean w.r.t. the number of operands for each
instruction defined, actually emit this to the InstrInfoDescriptor, which
allows an assert in the machineinstrbuilder to do some checking for us,
and is required by the dag->dag emitter

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@22895 91177308-0d34-0410-b5e6-96231b3b80d8