batman-adv: remove includes for extern declarations

It is not necessary to include the header for the struct definition for an
"extern " declaration. It can simply be dropped from the headers to reduce
the number of includes the preprocessor has to process. If needed, it can
be added to the actual C source file.

Signed-off-by: Sven Eckelmann <[e-mail]>
Signed-off-by: Simon Wunderlich <[e-mail]>

net/batman-adv/hard-interface.c

···
 #include <linux/minmax.h>
 #include <linux/mutex.h>
 #include <linux/netdevice.h>
+#include <linux/notifier.h>
 #include <linux/printk.h>
 #include <linux/rculist.h>
 #include <linux/rtnetlink.h>

net/batman-adv/hard-interface.h

···
 #include <linux/compiler.h>
 #include <linux/kref.h>
 #include <linux/netdevice.h>
-#include <linux/notifier.h>
 #include <linux/rcupdate.h>
 #include <linux/stddef.h>
 #include <linux/types.h>

net/batman-adv/mesh-interface.c

···
 #include <linux/string.h>
 #include <linux/types.h>
 #include <net/netlink.h>
+#include <net/rtnetlink.h>
 #include <uapi/linux/batadv_packet.h>
 #include <uapi/linux/batman_adv.h>
 

net/batman-adv/mesh-interface.h

···
 #include <linux/netdevice.h>
 #include <linux/skbuff.h>
 #include <linux/types.h>
-#include <net/rtnetlink.h>
 
 int batadv_skb_head_push(struct sk_buff *skb, unsigned int len);
 void batadv_interface_rx(struct net_device *mesh_iface,

net/batman-adv/netlink.h

···
 
 #include <linux/netlink.h>
 #include <linux/types.h>
-#include <net/genetlink.h>
 
 void batadv_netlink_register(void);
 void batadv_netlink_unregister(void);