Revert "[X86] Fix lowering to illegal type in LowerINSERT_VECTOR_ELT"

This reverts commit 6ff73ef.

Author: xiangzh1

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -18970,9 +18970,6 @@ SDValue X86TargetLowering::LowerINSERT_VECTOR_ELT(SDValue Op,
 
     MVT IdxSVT = MVT::getIntegerVT(EltSizeInBits);
     MVT IdxVT = MVT::getVectorVT(IdxSVT, NumElts);
-    if (!isTypeLegal(IdxSVT) || !isTypeLegal(IdxVT))
-      return SDValue();
-
     SDValue IdxExt = DAG.getZExtOrTrunc(N2, dl, IdxSVT);
     SDValue IdxSplat = DAG.getSplatBuildVector(IdxVT, dl, IdxExt);
     SDValue EltSplat = DAG.getSplatBuildVector(VT, dl, N1);