batman-adv: update copyright years

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
diff --git a/net/batman-adv/gateway_client.h b/net/batman-adv/gateway_client.h
index f0d129e..039902d 100644
--- a/net/batman-adv/gateway_client.h
+++ b/net/batman-adv/gateway_client.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2009-2012 B.A.T.M.A.N. contributors:
+/* Copyright (C) 2009-2013 B.A.T.M.A.N. contributors:
  *
  * Marek Lindner
  *