Adapt the preinit_config_board() to the board.json network changes. It
now looks for the device and the ports variables to configure the LAN
network.
This works with swconfig configurations.
Fixes: FS#3866
Fixes: d42640e389 ("base-files: use "ports" array in board.json network for bridges")
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>
Reviewed-by: Rafał Miłecki <rafal@milecki.pl>
(cherry picked from commit 467cd378db)
c0fdfd15fc