gprs_ns2: migrate to the new vty syntax

This also changes the vty configuration. If only timeout has been
configured for ns the new configuration is compatible.

For further information see:
https://osmocom.org/projects/libosmocore/wiki/Network_service_(NS)

Depends-on: I8c3f2afecc74b78f7f914f7dce166cbcb63444eb (libosmocore)
Change-Id: I14af821a8d1fda670643c3d5f81299a3abf3c583
diff --git a/src/pcu_main.cpp b/src/pcu_main.cpp
index ea7e341..003cabb 100644
--- a/src/pcu_main.cpp
+++ b/src/pcu_main.cpp
@@ -270,7 +270,7 @@
 		exit(1);
 	}
 	bssgp_set_bssgp_callback(gprs_gp_send_cb, pcu->nsi);
-	gprs_ns2_vty_init(pcu->nsi, NULL);
+	gprs_ns2_vty_init(pcu->nsi);
 
 	rc = vty_read_config_file(config_file, NULL);
 	if (rc < 0 && config_given) {
@@ -282,8 +282,6 @@
 		fprintf(stderr, "No config file: '%s' Using default config.\n",
 			config_file);
 
-	gprs_ns2_vty_create();
-
 	rc = telnet_init_dynif(tall_pcu_ctx, NULL, vty_get_bind_addr(),
 			       OSMO_VTY_PORT_PCU);
 	if (rc < 0) {