[mgcp] Add some parsing for RSIP messages coming in

This will just call a callback and leave all the handling
to the application.
diff --git a/openbsc/include/openbsc/mgcp.h b/openbsc/include/openbsc/mgcp.h
index 6a07cd1..37194be 100644
--- a/openbsc/include/openbsc/mgcp.h
+++ b/openbsc/include/openbsc/mgcp.h
@@ -77,6 +77,7 @@
 
 typedef int (*mgcp_change)(struct mgcp_config *cfg, int endpoint, int state, int local_rtp);
 typedef int (*mgcp_policy)(struct mgcp_config *cfg, int endpoint, int state, const char *transactio_id);
+typedef int (*mgcp_reset)(struct mgcp_config *cfg);
 
 struct mgcp_config {
 	int source_port;
@@ -97,6 +98,7 @@
 
 	mgcp_change change_cb;
 	mgcp_policy policy_cb;
+	mgcp_reset reset_cb;
 	void *data;
 
 	struct mgcp_endpoint *endpoints;