Revert "Add a target legalize hook for SplitVectorOperand"

This reverts commit 187198. It broke the bots.

The soft float test probably needs a -triple because of name differences.
On the hard float test I am getting a "roundss $1, %xmm0, %xmm0", instead of
"vroundss $1, %xmm0, %xmm0, %xmm0".

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@187201 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp

@@ -1031,10 +1031,6 @@ bool DAGTypeLegalizer::SplitVectorOperand(SDNode *N, unsigned OpNo) {
         dbgs() << "\n");
   SDValue Res = SDValue();
 
-  // See if the target wants to custom split this node.
-  if (CustomLowerNode(N, N->getOperand(OpNo).getValueType(), false))
-    return false;
-
   if (Res.getNode() == 0) {
     switch (N->getOpcode()) {
     default: