batman-adv: remove useless NULL check

debugfs_remove_recursive() checks whether its argument is not null
on its own, therefore it is possible to remove the external check.
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>

net/batman-adv/debugfs.c

@@ -396,10 +396,8 @@ void batadv_debugfs_init(void)
 
 void batadv_debugfs_destroy(void)
 {
-	if (batadv_debugfs) {
 	debugfs_remove_recursive(batadv_debugfs);
 	batadv_debugfs = NULL;
-	}
 }
 
 int batadv_debugfs_add_meshif(struct net_device *dev)