jf: Enable IDLETIMER which is used in netd

fixes: E/ConnectivityService(  549): Exception in setupDataActivityTracking java.lang.IllegalStateException: command '45 idletimer add rmnet_usb0 5 0' failed with '400 45 Failed to add interface'

Change-Id: I9c8ae3517dac1f260ac35135849979f8ca85d89d