batman-adv: Include main.h in bat_v_ogm.h

main.h includes statements which (re)define preprocessor variables which
influence the compiled code. This makes it necessary to include it in all
files. For example, it redefines pr_fmt used to the module as prefix for
each pr_* message.
Reported-by: Antonio Quartulli <a@unstable.cc>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

net/batman-adv/bat_v_ogm.h

@@ -18,10 +18,10 @@
 #ifndef _BATMAN_ADV_BATADV_V_OGM_H_
 #define _BATMAN_ADV_BATADV_V_OGM_H_
 
+#include "main.h"
+
 #include <linux/types.h>
 
-struct batadv_hard_iface;
-struct batadv_priv;
 struct sk_buff;
 
 int batadv_v_ogm_init(struct batadv_priv *bat_priv);