batman-adv: rename BATMAN_OGM_LEN to BATMAN_OGM_HLEN

Using BATMAN_OGM_LEN leaves one with the impression that this is
the full packet size which is not the case. Therefore the variable
is renamed.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>
diff --git a/net/batman-adv/packet.h b/net/batman-adv/packet.h
index 59800e8..59dec0a 100644
--- a/net/batman-adv/packet.h
+++ b/net/batman-adv/packet.h
@@ -126,7 +126,7 @@
 	uint16_t tt_crc;
 } __packed;
 
-#define BATMAN_OGM_LEN sizeof(struct batman_ogm_packet)
+#define BATMAN_OGM_HLEN sizeof(struct batman_ogm_packet)
 
 struct icmp_packet {
 	struct batman_header header;