batman-adv: update copyright years for 2015

Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
diff --git a/net/batman-adv/multicast.h b/net/batman-adv/multicast.h
index 3a44ebd..033d80e 100644
--- a/net/batman-adv/multicast.h
+++ b/net/batman-adv/multicast.h
@@ -1,4 +1,4 @@
-/* Copyright (C) 2014 B.A.T.M.A.N. contributors:
+/* Copyright (C) 2014-2015 B.A.T.M.A.N. contributors:
  *
  * Linus Lüssing
  *