Update copyright line to 2015
diff --git a/include/polarssl/xtea.h b/include/polarssl/xtea.h
index f3cb9a1..8f47e8a 100644
--- a/include/polarssl/xtea.h
+++ b/include/polarssl/xtea.h
@@ -3,7 +3,7 @@
  *
  * \brief XTEA block cipher (32-bit)
  *
- *  Copyright (C) 2006-2013, ARM Limited, All Rights Reserved
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *
  *  This file is part of mbed TLS (https://polarssl.org)
  *