Use port number #defines for VTY and CTRL ports

.. as defined in libosmocore
diff --git a/openbsc/src/osmo-bsc_mgcp/mgcp_main.c b/openbsc/src/osmo-bsc_mgcp/mgcp_main.c
index 16fb722..bee1276 100644
--- a/openbsc/src/osmo-bsc_mgcp/mgcp_main.c
+++ b/openbsc/src/osmo-bsc_mgcp/mgcp_main.c
@@ -44,7 +44,7 @@
 
 #include <osmocom/vty/telnet_interface.h>
 #include <osmocom/vty/logging.h>
-
+#include <osmocom/vty/ports.h>
 #include <osmocom/vty/command.h>
 
 #include "../../bscconfig.h"
@@ -228,7 +228,7 @@
 	if (rc < 0)
 		return rc;
 
-	rc = telnet_init(tall_bsc_ctx, &dummy_network, 4243);
+	rc = telnet_init(tall_bsc_ctx, &dummy_network, OSMO_VTY_PORT_BSC_MGCP);
 	if (rc < 0)
 		return rc;