kerndat: call kerndat_link_nsid()

It was droped during one of rebases.
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>

criu/kerndat.c

@@ -886,6 +886,8 @@ int kerndat_init(void)
 		ret = kerndat_socket_netns();
 	if (!ret)
 		ret = kerndat_nsid();
+	if (!ret)
+		ret = kerndat_link_nsid();
 	if (!ret)
 		ret = kerndat_has_memfd_create();
 	if (!ret)