batman-adv: add debugfs structure for information per interface

To show information per interface, add a debugfs hardif structure
similar to the system in sysfs. Hard interface folders will be created
in "$debugfs/batman-adv/". Files are not yet added.

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>
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 1409279..529b374 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -84,6 +84,7 @@
  * @rcu: struct used for freeing in an RCU-safe manner
  * @bat_iv: BATMAN IV specific per hard interface data
  * @cleanup_work: work queue callback item for hard interface deinit
+ * @debug_dir: dentry for nc subdir in batman-adv directory in debugfs
  */
 struct batadv_hard_iface {
 	struct list_head list;
@@ -98,6 +99,7 @@
 	struct rcu_head rcu;
 	struct batadv_hard_iface_bat_iv bat_iv;
 	struct work_struct cleanup_work;
+	struct dentry *debug_dir;
 };
 
 /**