Revert "DAG: Check if extract_vector_elt is legal or custom"

This reverts r295782. This could potentially result in some
legalization loops and I avoided the need for this.

llvm-svn: 296393

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -7907,7 +7907,7 @@ SDValue DAGCombiner::visitTRUNCATE(SDNode *N) {
     EVT SrcVT = VecSrc.getValueType();
     if (SrcVT.isVector() && SrcVT.getScalarType() == VT &&
         (!LegalOperations ||
-         TLI.isOperationLegalOrCustom(ISD::EXTRACT_VECTOR_ELT, SrcVT))) {
+         TLI.isOperationLegal(ISD::EXTRACT_VECTOR_ELT, SrcVT))) {
       SDLoc SL(N);
 
       EVT IdxVT = TLI.getVectorIdxTy(DAG.getDataLayout());