Ondřej Caletka authored Nov 19, 2016 and Michal Hrusecky committed Nov 24, 2016

Since there is no simply accessible serial console, it may be handy to
have a SSH recovery mode. This patch adds new rescue mode, activated by
holding the reset button until five LEDs are lit.

In this mode, the eth0 interface is set up using IP address
192.168.1.1/24 and the switch is configured so eth0 is interconnected
exclusivelly with the LAN4 port. Dropbear SSH server is started,
accepting root login without password.

This patch requires dropbear to be compiled inside the rescue image.

Signed-off-by: Ondřej Caletka <ondrej@caletka.cz>