batman-adv: Add the backbone gateway list to debugfs

This is especially useful if there are no claims yet, but we still want
to know which gateways are using bridge loop avoidance in the network.

Signed-off-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/bridge_loop_avoidance.h b/net/batman-adv/bridge_loop_avoidance.h
index 3f0dfa2..789cb73 100644
--- a/net/batman-adv/bridge_loop_avoidance.h
+++ b/net/batman-adv/bridge_loop_avoidance.h
@@ -27,6 +27,8 @@
 int batadv_bla_is_backbone_gw(struct sk_buff *skb,
 			      struct batadv_orig_node *orig_node, int hdr_size);
 int batadv_bla_claim_table_seq_print_text(struct seq_file *seq, void *offset);
+int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq,
+					     void *offset);
 int batadv_bla_is_backbone_gw_orig(struct batadv_priv *bat_priv, uint8_t *orig);
 int batadv_bla_check_bcast_duplist(struct batadv_priv *bat_priv,
 				   struct batadv_bcast_packet *bcast_packet,
@@ -65,6 +67,12 @@
 	return 0;
 }
 
+static inline int batadv_bla_backbone_table_seq_print_text(struct seq_file *seq,
+							   void *offset)
+{
+	return 0;
+}
+
 static inline int batadv_bla_is_backbone_gw_orig(struct batadv_priv *bat_priv,
 						 uint8_t *orig)
 {