message: Fix BiasAddGradShape for NCHW, channel should be second from the left,
  not third-from-right as we could have 3/4/5 dimensional cases
diff: @@ -266,7 +266,7 @@ Status BiasAddGradShape(shape_inference::InferenceContext* c) {
  if (s.ok() && data_format == "NCHW") {
  TF_RETURN_IF_ERROR(c->WithRankAtLeast(c->input(0), 3, &input_shape));
  - c->set_output(0, c->Vector(c->Dim(input_shape, -3)));
  + c->set_output(0, c->Vector(c->Dim(input_shape, 1)));
  } else {
  TF_RETURN_IF_ERROR(c->WithRankAtLeast(c->input(0), 2, &input_shape));
  c->set_output(0, c->Vector(c->Dim(input_shape, -1)));
  