hnbgw: vty: set explicit go_parent_cb

A second level of depth will be added to the hnbgw node soon, which will need
explicit go-parent logic.

Change-Id: I8d1c18a396c215e8425ae49872b5c73316087d7d
diff --git a/src/hnbgw.c b/src/hnbgw.c
index 2eecbea..16a2e43 100644
--- a/src/hnbgw.c
+++ b/src/hnbgw.c
@@ -346,6 +346,7 @@
 static struct vty_app_info vty_info = {
 	.name		= "OsmoHNBGW",
 	.version	= "0",
+	.go_parent_cb	= hnbgw_vty_go_parent,
 };
 
 static struct {