lantiq: add missing default lan interface

With removing the boards from the the default case to fix the xDSL WAN
MAC-Address, the setting for the default LAN interface wasn't added.

Fixes: 92a12c43 ("lantiq: fix avm fritz box mac addresses")

Signed-off-by: Mathias Kresin <dev@kresin.me>

target/linux/lantiq/base-files/etc/board.d/02_network

@@ -117,10 +117,12 @@ EASY80920NAND|EASY80920NOR)
 
 FRITZ3370)
 	wan_mac=$(macaddr_add "$(mtd_get_mac_binary urlader 2439)" 1)
+	ucidef_set_interface_lan 'eth0'
 	;;
 
 FRITZ7320)
 	wan_mac=$(macaddr_add "$(mtd_get_mac_binary urlader 2705)" 1)
+	ucidef_set_interface_lan 'eth0'
 	;;
 
 FRITZ7360SL)