batman-adv: types, Fix comment on bcast_own

batadv_orig_bat_iv->bcast_own is actually not a bitfield, it is an
array. Adjust the comment accordingly.

Signed-off-by: Markus Pargmann <mpa@pengutronix.de>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>