kirkwood: set default EA4500 switch config

This maps the LAN ports to eth0 and WAN port to eth1.
Since there are two interfaces the 802.1q VLAN mode
is unnecessary and left disabled. Port-based VLANs
are used instead.

Signed-off-by: Claudio Leite <leitec@staticky.com>

SVN-Revision: 43750