Fix confusing machine verifier error.

The error reported the number of explicit operands,
but that isn't what is checked. In my case, this
resulted in the confusing errors

"Too few operands." followed shortly by
"8 operands expected, but 8 given."

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194862 91177308-0d34-0410-b5e6-96231b3b80d8