Replace relu6 with ReLU layers (#10597)

* Remove unused relu6

* Remove doc for loading relu6

docs/templates/applications.md

@@ -533,15 +533,6 @@ MobileNet model, with weights pre-trained on ImageNet.
 
 Note that this model only supports the data format `'channels_last'` (height, width, channels).
 
-To load a MobileNet model via `load_model`, import the custom object `relu6` and pass it to the `custom_objects` parameter.
-
-E.g.
-
-```python
-model = load_model('mobilenet.h5', custom_objects={
-                   'relu6': mobilenet.relu6})
-```
-
 The default input size for this model is 224x224.
 
 ### Arguments
@@ -732,15 +723,6 @@ MobileNetV2 model, with weights pre-trained on ImageNet.
 
 Note that this model only supports the data format `'channels_last'` (height, width, channels).
 
-To load a MobileNetV2 model via `load_model`, import the custom object `relu6` and pass it to the `custom_objects` parameter.
-
-E.g.
-
-```python
-model = load_model('mobilenet_v2.h5', custom_objects={
-                   'relu6': mobilenetv2.relu6})
-```
-
 The default input size for this model is 224x224.
 
 ### Arguments

keras/applications/mobilenet.py

@@ -4,7 +4,6 @@ from __future__ import print_function
 
 from keras_applications import mobilenet
 
-relu6 = mobilenet.relu6
 MobileNet = mobilenet.MobileNet
 decode_predictions = mobilenet.decode_predictions
 preprocess_input = mobilenet.preprocess_input

keras/applications/mobilenetv2.py

@@ -4,7 +4,6 @@ from __future__ import print_function
 
 from keras_applications import mobilenet_v2
 
-relu6 = mobilenet_v2.relu6
 MobileNetV2 = mobilenet_v2.MobileNetV2
 decode_predictions = mobilenet_v2.decode_predictions
 preprocess_input = mobilenet_v2.preprocess_input