batman-adv: Use "__attribute__" shortcut macros

Linux 2.6.21 defines different macros for __attribute__ which are also
used inside batman-adv. The next version of checkpatch.pl warns about
the usage of __attribute__((packed))).

Linux 2.6.33 defines an extra macro __always_unused which is used to
assist source code analyzers and can be used to removed the last
existing __attribute__ inside the source code.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 97cb23d..bf3f6f5 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -246,13 +246,13 @@
 	/* this packet might be part of the vis send queue. */
 	struct sk_buff *skb_packet;
 	/* vis_info may follow here*/
-} __attribute__((packed));
+} __packed;
 
 struct vis_info_entry {
 	uint8_t  src[ETH_ALEN];
 	uint8_t  dest[ETH_ALEN];
 	uint8_t  quality;	/* quality = 0 means HNA */
-} __attribute__((packed));
+} __packed;
 
 struct recvlist_node {
 	struct list_head list;