batman-adv: Avoid double freeing of bat_counters

On errors in batadv_mesh_init(), bat_counters will be freed in both
batadv_mesh_free() and batadv_softif_init_late(). This patch fixes this
by returning earlier from batadv_softif_init_late() in case of errors in
batadv_mesh_init() and by setting bat_counters to NULL after freeing.

Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/soft-interface.c b/net/batman-adv/soft-interface.c
index 6f20d33..819dfb0 100644
--- a/net/batman-adv/soft-interface.c
+++ b/net/batman-adv/soft-interface.c
@@ -505,6 +505,7 @@
 	batadv_debugfs_del_meshif(dev);
 free_bat_counters:
 	free_percpu(bat_priv->bat_counters);
+	bat_priv->bat_counters = NULL;
 
 	return ret;
 }