[target/linux/lantiq] change /etc/config/network according to actual VLAN config...

[target/linux/lantiq] change /etc/config/network according to actual VLAN config to enable LAN port 4 on the ARV4520PW board

The VLAN mapping on the ARV4520PW board is the following:

port on Router: | VLAN in software:
LAN 1           | 3
LAN 2           | 2
LAN 3           | 1
LAN 4           | 0
DSL             | 4

So LAN4 is not VLAN4 but VLAN0 (VLAN4 is DSL port) -> set "3 2 1 0 5t" as default switch config.

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@31391 3c298f89-4303-0410-b956-a3cf2f4a3e73