kirkwood: drop port-based VLAN setup

kirkwood: drop port-based VLAN setup

Using port-based VLANs depends on a non-standard
swconfig parameter, which compilcates things like
LuCI that don't know about it. This patch changes
the default to use 802.1q VLANs internally in the
switch, but without tagging packets since we have
two Ethernet ports.

iperf3 tests indicate no difference in performance
versus port-based VLANs when the CPU port is not
using tags.

Signed-off-by: Claudio Leite <leitec@staticky.com>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@44122 3c298f89-4303-0410-b956-a3cf2f4a3e73