Found mobile_network_settings preference is dependent on toggle_airplane
preference so once Disallow_airplane_mode is turned on, toggle_airplane
preference will be set disabled, and mobile_network_settings preference
is also set disabled because of the dependence. Can fix this bug moving
the dependance and let MobileNetworkPreferenceController listen to
Settings.Global.AIRPLANE_MODE_ON.
Bug: 76468718
Test: manually but TestDpc
Change-Id: I137938766557d7bc5ae0795bc3359a6bfbae17e3
6e78482016