ramips: fix network setup for various NETGEAR boards

There are currently the following issues present for the Netgear R6220,
R6350 and WNDR3700 v5:

 - LAN and WAN MAC-addresses are inverted
 - WAN MAC-address is off. It are +2 compared to the LAN MAC-address
   (R6350 only)
 - Switchport order is inverted in LuCi

This commit fixes both these issues by assigning correct MAC-addresses
to LAN and WAN interfaces and defining the switchports with the correct
labels.

Signed-off-by: David Bauer <mail@david-bauer.net>