batman-adv: consolidate duplicated primary_if checking code

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/main.h b/net/batman-adv/main.h
index d57b746..5c0be5b 100644
--- a/net/batman-adv/main.h
+++ b/net/batman-adv/main.h
@@ -153,6 +153,8 @@
 void batadv_inc_module_count(void);
 void batadv_dec_module_count(void);
 int batadv_is_my_mac(const uint8_t *addr);
+struct batadv_hard_iface *
+batadv_seq_print_text_primary_if_get(struct seq_file *seq);
 int batadv_batman_skb_recv(struct sk_buff *skb, struct net_device *dev,
 			   struct packet_type *ptype,
 			   struct net_device *orig_dev);