batman-adv: Drop lockdep.h include for soft-interface.c

The commit ab92d68f ("net: core: add generic lockdep keys") removed
all lockdep functionality from soft-interface.c but didn't remove the
include for this functionality.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/soft-interface.c

@@ -22,7 +22,6 @@
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/list.h>
-#include <linux/lockdep.h>
 #include <linux/netdevice.h>
 #include <linux/netlink.h>
 #include <linux/percpu.h>