base-files: failsafe: Fix IP configuration

base-files: failsafe: Fix IP configuration

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: d42640e389a8 ("base-files: use "ports" array in board.json network for bridges")
Signed-off-by: Hauke Mehrtens <[email protected]>
Reviewed-by: Rafał Miłecki <[email protected]>
(cherry picked from commit 467cd378db3359814866ec4121fdb4417783241e)