Add check that output is quantized. (#1830)

BUG=http://b/267818294

Author: tanmaydas82

tensorflow/lite/micro/kernels/add_common.cc

@@ -39,6 +39,8 @@ TfLiteStatus CalculateOpDataAdd(TfLiteContext* context, TfLiteAddParams* params,
   data->requires_broadcast = !HaveSameShapes(input1, input2);
 
   if (output->type == kTfLiteInt8 || output->type == kTfLiteInt16) {
+    TFLITE_CHECK_NE(output->quantization.type, kTfLiteNoQuantization);
+
     // 8bit -> 8bit general quantized path, with general rescalings
     data->input1_offset = -input1->params.zero_point;
     data->input2_offset = -input2->params.zero_point;