ath79: align Ubiquiti AC Pro ethernet map to factory

ath79: align Ubiquiti AC Pro ethernet map to factory

The Uniquiti AC Pro and Ubiquiti AC Mesh Pro currently have the
"Primary" and "Secondary" ethernet ports configured to offer LAN as well
as WAN. However, Uiquiti describes the following behavior for the
devices Ethernet ports:

 > Secondary UniFi Access Point (UAP) Ethernet ports don't
 > provide PoE passthrough (to run current to a second powered
 > device), but they do support data passthrough.
 > It serves as a bridged interface between main / secondary
 > Ethernet port.

To reduce confusion for users (as LAN and WAN functionality is not
visible on the device itself), configure both ports to offer LAN
functionality. Users can still configure a WAN interface on a port they
are able to choose.

CC: Lucian Cristian <lucian.cristian@gmail.com>
Reported-by: Florian Klink <flokli@flokli.de>
Signed-off-by: David Bauer <mail@david-bauer.net>