mgcp: Include a MGCP Response String in the response

Switch to a \r\n at the end of the query. Both \n and \r\n
are valid according to the spec but this makes us match
responses of other equipment.
diff --git a/openbsc/include/openbsc/mgcp.h b/openbsc/include/openbsc/mgcp.h
index 26a6c33..04643c5 100644
--- a/openbsc/include/openbsc/mgcp.h
+++ b/openbsc/include/openbsc/mgcp.h
@@ -151,7 +151,7 @@
  * format helper functions
  */
 struct msgb *mgcp_handle_message(struct mgcp_config *cfg, struct msgb *msg);
-struct msgb *mgcp_create_response_with_data(int code, const char *msg, const char *trans, const char *data);
+struct msgb *mgcp_create_response_with_data(int code, const char *txt, const char *msg, const char *trans, const char *data);
 
 /* adc helper */
 static inline int mgcp_timeslot_to_endpoint(int multiplex, int timeslot)