The TL-WR842N v2 has the following switch port layout with swconfig port 0
being connected to eth1:
Power LAN4 LAN3 LAN2 LAN1 WAN USB
(*) | [...] | [...] | [...] | [...] | [...] | [.]
swconfig port: 1 4 3 2 n/a
netdev: eth1 eth1 eth1 eth1 eth0
Adjust the board defaults to match this model specific layout.
Signed-off-by: Jo-Philipp Wich <jo@mein.io>