batman-adv: fix size of batadv_bla_claim_dst

Since this is a mac address and always 48 bit, and we can assume that
it is always aligned to 2-byte boundaries, add a pack(2) pragma.
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>

net/batman-adv/packet.h

@@ -155,6 +155,7 @@ enum batadv_tvlv_type {
 	BATADV_TVLV_ROAM	= 0x05,
 };
 
+#pragma pack(2)
 /* the destination hardware field in the ARP frame is used to
  * transport the claim type and the group id
  */
@@ -163,6 +164,7 @@ struct batadv_bla_claim_dst {
 	uint8_t type;		/* bla_claimframe */
 	__be16 group;		/* group id */
 };
+#pragma pack()
 
 /**
  * struct batadv_ogm_packet - ogm (routing protocol) packet