mako: Reorder tetherable connection types

* In O, the default setting for mobile data always active was
  changed from off to on, meaning that when non-WiFi tethering
  is being attempted, more than one connection can be active
* Since the first active connection type in this overlay is used,
  reorder the values to get WiFi connections first, and then
  any type of mobile data connection, instead of vice versa

Change-Id: I41f31ba1a2793e209ff439c9ba28a390fecdeecb