[SelectionDAGBuilder] Remove unneeded vector bitcast from visitTargetIntrinsic.

[craig.topper]

Summary

This seems to be a leftover from a long time ago when there was
an ISD::VBIT_CONVERT and a MVT::Vector. It looks like in those days
the vector type was carried in a VTSDNode.

As far as I know, these days ComputeValueTypes would have already
assigned "Result" the same type we're getting from TLI.getValueType
here. Thus the BITCAST is always a NOP. Verified by adding an assert
and running check-llvm.

[efriedma]

LGTM

llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

if (HasChain) {
     SDValue Chain = Result.getValue(Result.getNode()->getNumValues()-1);
     if (OnlyLoad)
       PendingLoads.push_back(Chain);
     else
       DAG.setRoot(Chain);
   }
 
   if (!I.getType()->isVoidTy()) {
-    if (VectorType *PTy = dyn_cast<VectorType>(I.getType())) {
-      EVT VT = TLI.getValueType(DAG.getDataLayout(), PTy);
-      Result = DAG.getNode(ISD::BITCAST, getCurSDLoc(), VT, Result);
-    } else
+    if (!isa<VectorType>(I.getType()))
       Result = lowerRangeToAssertZExt(DAG, I, Result);
 
     MaybeAlign Alignment = I.getRetAlign();
     if (!Alignment)
       Alignment = F->getAttributes().getRetAlignment();
     // Insert `assertalign` node if there's an alignment.
     if (InsertAssertAlign && Alignment) {
       Result =