[x86] Fix -Wunused-value in X86ISelLowering.cpp (NFC)

llvm-project/llvm/lib/Target/X86/X86ISelLowering.cpp:28530:16:
error: left operand of comma operator has no effect [-Werror,-Wunused-value]
        return VT, DAG.getNode(ISD::OR, dl, VT, RLo, DAG.getBitcast(VT, RHi));
               ^~
1 error generated.

Author: DamonFool

llvm/lib/Target/X86/X86ISelLowering.cpp

@@ -28527,7 +28527,7 @@ static SDValue LowerMUL(SDValue Op, const X86Subtarget &Subtarget,
         RLo = DAG.getNode(ISD::AND, dl, VT, DAG.getBitcast(VT, RLo), Mask);
         RHi = DAG.getNode(X86ISD::VSHLI, dl, ExVT, RHi,
                           DAG.getTargetConstant(8, dl, MVT::i8));
-        return VT, DAG.getNode(ISD::OR, dl, VT, RLo, DAG.getBitcast(VT, RHi));
+        return DAG.getNode(ISD::OR, dl, VT, RLo, DAG.getBitcast(VT, RHi));
       }
     }