You don’t have to downgrade Keras 2.2.2.
In Keras 2.2.2 there is no _obtain_input_shape method in the keras.applications.imagenet_utils module. You can find it under keras-applications with the modul name keras_applications (underscore).
So you don’t have to downgrade your Keras to 2.2.0 just change:
from keras.applications.imagenet_utils import _obtain_input_shape
to
from keras_applications.imagenet_utils import _obtain_input_shape