Squash to "selftests/bpf: Add mptcp subflow subtest"

create_netns() is updated in "bpf-next add netns helpers" series,
test_subflow() needs to be updated too.

That means v3 of "selftests/bpf: new MPTCP subflow subtest" cannot be sent
to bpf-next at the moment until this "bpf-next add netns helpers" series is
accepted.

Signed-off-by: Geliang Tang <tanggeliang@kylinos.cn>

tools/testing/selftests/bpf/prog_tests/mptcp.c

@@ -413,7 +413,7 @@ static void test_subflow(void)
 	if (!ASSERT_OK(err, "prog_attach"))
 		goto skel_destroy;
 
-	nstoken = create_netns();
+	nstoken = create_netns(NS_TEST);
 	if (!ASSERT_OK_PTR(nstoken, "create_netns: mptcp_subflow"))
 		goto skel_destroy;