batman-adv: set up network coding packet handlers during module init

batman-adv saves its table of packet handlers as a global state, so handlers
must be set up only once (and setting them up a second time will fail).

The recently-added network coding support tries to set up its handler each time
a new softif is registered, which obviously fails when more that one softif is
used (and in consequence, the softif creation fails).

Fix this by splitting up batadv_nc_init into batadv_nc_init (which is called
only once) and batadv_nc_mesh_init (which is called for each softif); in
addition batadv_nc_free is renamed to batadv_nc_mesh_free to keep naming
consistent.

Signed-off-by: Matthias Schiffer <mschiffer@universe-factory.net>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
diff --git a/net/batman-adv/main.c b/net/batman-adv/main.c
index c72d1bc..1356af6 100644
--- a/net/batman-adv/main.c
+++ b/net/batman-adv/main.c
@@ -65,6 +65,7 @@
 	batadv_recv_handler_init();
 
 	batadv_iv_init();
+	batadv_nc_init();
 
 	batadv_event_workqueue = create_singlethread_workqueue("bat_events");
 
@@ -142,7 +143,7 @@
 	if (ret < 0)
 		goto err;
 
-	ret = batadv_nc_init(bat_priv);
+	ret = batadv_nc_mesh_init(bat_priv);
 	if (ret < 0)
 		goto err;
 
@@ -167,7 +168,7 @@
 	batadv_vis_quit(bat_priv);
 
 	batadv_gw_node_purge(bat_priv);
-	batadv_nc_free(bat_priv);
+	batadv_nc_mesh_free(bat_priv);
 	batadv_dat_free(bat_priv);
 	batadv_bla_free(bat_priv);