batman-adv: initialise last_ttvn and tt_crc for the orig_node structure

The last_ttvn and tt_crc fields of the orig_node structure were not
initialised causing an immediate TT_REQ/RES dialogue even if not needed.

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