libosmo-mgcp-client is GPLv2+, not AGPLv3+

The client library should be usable to all GPLv2/v3/AGPLv2/v3 programs,
so like our general project practises, let's put it under
GPLv2-or-later.  I believe this was unintentional from the beginning.

Our general policy has been:
* libraries under GPLv2-or-later
* applications under AGPLv3-or-later

Change-Id: I29ed7edc510dba67d28b9247aecb4d6d5d25cc0c
diff --git a/src/libosmo-mgcp-client/mgcp_client.c b/src/libosmo-mgcp-client/mgcp_client.c
index efe1d1f..7476197 100644
--- a/src/libosmo-mgcp-client/mgcp_client.c
+++ b/src/libosmo-mgcp-client/mgcp_client.c
@@ -4,16 +4,16 @@
  * All Rights Reserved
  *
  * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU Affero General Public License as published by
- * the Free Software Foundation; either version 3 of the License, or
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU Affero General Public License for more details.
+ * GNU General Public License for more details.
  *
- * You should have received a copy of the GNU Affero General Public License
+ * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  *
  */