Switch LAN and WAN port of Ubiquiti AirGateway

This makes the LAN port the PoE master, so the AirGateway can be used to
supply power to another node connected via mesh-on-LAN.

Fixes #608

package/gluon-core/luasrc/lib/gluon/upgrade/020-interfaces

@@ -34,6 +34,7 @@ if platform.match('ar71xx', 'generic', {
 	'cpe510',
 	'wbs210',
 	'wbs510',
+	'airgateway',
 	'nanostation-m',
 	'nanostation-m-xw',
 	'unifi-outdoor-plus',

package/gluon-setup-mode/luasrc/lib/gluon/upgrade/320-setup-ifname

@@ -8,10 +8,18 @@ if sysconfig.setup_ifname then
 	os.exit(0)
 end
 
-if
-  platform.match('ar71xx', 'generic', {'cpe210', 'cpe510', 'wbs210', 'wbs510', 'nanostation-m', 'nanostation-m-xw', 'unifi-outdoor-plus', 'uap-pro', 'unifiac-pro'}) or
-  platform.match('ar71xx', 'mikrotik')
-then
+if platform.match('ar71xx', 'generic', {
+	'cpe210',
+	'cpe510',
+	'wbs210',
+	'wbs510',
+	'airgateway',
+	'nanostation-m',
+	'nanostation-m-xw',
+	'unifi-outdoor-plus',
+	'uap-pro',
+	'unifiac-pro'
+}) or platform.match('ar71xx', 'mikrotik') then
 	sysconfig.setup_ifname = sysconfig.config_ifname or sysconfig.wan_ifname or sysconfig.lan_ifname
 else
 	sysconfig.setup_ifname = sysconfig.config_ifname or sysconfig.lan_ifname or sysconfig.wan_ifname