Fixed race conditions in GeofenceHardwareImpl.

Fixed b/8725226
1. Check if a geofence is registered before calling removeGeofence,
pauseGeofence and resumeGeofence
2. Moved add/remove operation of mGeofences from handler thread to
binder thread to fix potential race conditions by REMOVE_GEOFENCE.

Change-Id: I1c68a49ac4a08324c13702ba9013d2adf031aed9
1 file changed