batman-adv: correctly pass the client flag on tt_response

When a TT response with the full table is sent, the client flags
should be sent as well. This patch fix the flags assignment when
populating the tt_response to send back

This was introduced by 30cfd02b


("batman-adv: detect not yet announced clients")

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>