[MAINTAINERS]: netfilter@ is subscribers-only

netfilter mailing list is subscribers-only.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -2288,7 +2288,7 @@ P:	Jozsef Kadlecsik
 P:	Patrick McHardy
 M:	kaber@trash.net
 L:	netfilter-devel@lists.netfilter.org
-L:	netfilter@lists.netfilter.org
+L:	netfilter@lists.netfilter.org (subscribers-only)
 L:	coreteam@netfilter.org
 W:	http://www.netfilter.org/
 W:	http://www.iptables.org/