This is based on the LEDE pull request as on 2017-10-17.

Tested successfully on device (including flashing factory
image, no TFTP).

Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Tested-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>
Reviewed-by: Tim Niemeyer <tim@tn-x.org>