batman-adv: don't add TEMP clients belonging to other backbone nodes

batman-adv: don't add TEMP clients belonging to other backbone nodes

The "early client detection" mechanism must not add clients belonging
to other backbone nodes. Such clients must be reached by directly
using the LAN instead of the mesh.

This was introduced by a2d1af4d55bf5051dba48e44e4ba4514fe09bc91
("batman-adv: detect not yet announced clients")

Reported-by: Glen Page <glen.page@thet.net>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>