batman-adv: remove unnecessary logspam

This patch removes unnecessary logspam which resulted from superfluous
calls to net_ratelimit(). With the supplied patch, net_ratelimit() is
called after the loglevel has been checked.

Signed-off-by: André Gaul <gaul@web-yard.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>