Update copyright line to 2015
diff --git a/library/gcm.c b/library/gcm.c
index e294a97..5b39867 100644
--- a/library/gcm.c
+++ b/library/gcm.c
@@ -1,7 +1,7 @@
 /*
  *  NIST SP800-38D compliant GCM implementation
  *
- *  Copyright (C) 2006-2012, ARM Limited, All Rights Reserved
+ *  Copyright (C) 2006-2015, ARM Limited, All Rights Reserved
  *
  *  This file is part of mbed TLS (https://polarssl.org)
  *