gprs_ns2: drop gprs_ns2_vty, rename vty2 -> vty

Drop the vty(1) code and replace it with vty2. The vty(1) was only
used as intermediate to not develop a vty while developing a new
code base behind. Users of gprs_ns2_ has to use the new vty code.

API change which must be synchronized with osmo-pcu,
osmo-gbproxy, osmo-sgsn.

Change-Id: Ic2059e75d8ede8e5c29c4fef6be608ed79c8a97c
diff --git a/utils/osmo-ns-dummy.c b/utils/osmo-ns-dummy.c
index 58e8152..33949d3 100644
--- a/utils/osmo-ns-dummy.c
+++ b/utils/osmo-ns-dummy.c
@@ -230,7 +230,7 @@
 	}
 
 	gprs_ns2_dynamic_create_nse(nsi, true);
-	gprs_ns2_vty2_init(nsi);
+	gprs_ns2_vty_init(nsi);
 	rc = vty_read_config_file(config_file, NULL);
 	if (rc < 0 && config_given) {
 		fprintf(stderr, "Failed to parse the config file: '%s'\n",