batman-adv: fix neigh_ifinfo imbalance

The neigh_ifinfo object must be freed if it has been used in
batadv_iv_ogm_process_per_outif().

This is a regression introduced by
89652331c00f43574515059ecbf262d26d885717
("batman-adv: split tq information in neigh_node struct")

Reported-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Simon Wunderlich <simon@open-mesh.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>