[X86] Remove a DCI.isBeforeLegalize() call from combineVSelectWithAllOnesOrZeros.

This was blocking isTypeLegal call so that we could do a particular
transform on illegal types before type legalization. But the we
create a target specific node using that type. We shouldn't do
that if the type isn't legal. So I think we should just always
make sure the type is legal.

I suspect that in order to get the condition VT to not be a vector
of i1 we already completed type legalization anyway so this probably
doesn't matter much in practice.

Author: topperc

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -39608,7 +39608,7 @@ combineVSelectWithAllOnesOrZeros(SDNode *N, SelectionDAG &DAG,
   if (TValIsAllOnes && FValIsAllZeros)
     return DAG.getBitcast(VT, Cond);
 
-  if (!DCI.isBeforeLegalize() && !TLI.isTypeLegal(CondVT))
+  if (!TLI.isTypeLegal(CondVT))
     return SDValue();
 
   // vselect Cond, 111..., X -> or Cond, X