Fix/Update copyright notices; Add SPDX annotation

Let's fix some erroneous/accidential references to wrong license,
update copyright information where applicable and introduce a
SPDX-License-Identifier to all files.

Change-Id: I39af26c6aaaf5c926966391f6565fc5936be21af
diff --git a/src/gsm/tlv_parser.c b/src/gsm/tlv_parser.c
index b1b1034..ead856c 100644
--- a/src/gsm/tlv_parser.c
+++ b/src/gsm/tlv_parser.c
@@ -1,7 +1,10 @@
-/* (C) 2008-2010 by Harald Welte <laforge@gnumonks.org>
+/* (C) 2008-2017 by Harald Welte <laforge@gnumonks.org>
+ * (C) 2016-2017 by sysmocom - s.f.m.c. GmbH
  *
  * All Rights Reserved
  *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  * the Free Software Foundation; either version 2 of the License, or