Set up eth0 as LAN interface by default.

Backport of r46174
Signed-off-by: Florian Fainelli <florian@openwrt.org>


git-svn-id: svn://svn.openwrt.org/openwrt/branches/chaos_calmer@46419 3c298f89-4303-0410-b956-a3cf2f4a3e73