batman-adv: use NO_FLAGS define instead of hard-coding 0

The definition NO_FLAGS was introduced to make the code more
readable and shall be used to initialize flag fields.

Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index a3fbfb5..b55e861 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -337,7 +337,7 @@
 	batman_packet = (struct batman_packet *)(hard_iface->packet_buff);
 	batman_packet->packet_type = BAT_PACKET;
 	batman_packet->version = COMPAT_VERSION;
-	batman_packet->flags = 0;
+	batman_packet->flags = NO_FLAGS;
 	batman_packet->ttl = 2;
 	batman_packet->tq = TQ_MAX_VALUE;
 	batman_packet->num_tt = 0;