batman-adv: don't let backbone gateways exchange tt entries

As the backbone gateways are connected to the same backbone, they
should announce the same clients on the backbone non-exclusively.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

diff --cc net/batman-adv/bridge_loop_avoidance.c
Simple merge

diff --cc net/batman-adv/bridge_loop_avoidance.h
Simple merge

diff --cc net/batman-adv/routing.c
Simple merge

diff --cc net/batman-adv/translation-table.c
Simple merge