gprs_ns2_vty: fix memory leak of vty_binds

They never got freed, only removed from the vty_bind queue.

Change-Id: I100897c32dc152f9acbb322782fae49b1f0bc030
diff --git a/src/gb/gprs_ns2_vty.c b/src/gb/gprs_ns2_vty.c
index 978c73b..3646080 100644
--- a/src/gb/gprs_ns2_vty.c
+++ b/src/gb/gprs_ns2_vty.c
@@ -128,6 +128,7 @@
 		return;
 
 	llist_del(&vbind->list);
+	talloc_free(vbind);
 }
 
 static struct cmd_node ns_node = {