Phonet: phonet_net_id can be static (sparse)

Signed-off-by: NRémi Denis-Courmont <remi.denis-courmont@nokia.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/phonet/pn_dev.c

@@ -44,7 +44,7 @@ struct phonet_net {
 	struct phonet_routes routes;
 };
 
-int phonet_net_id __read_mostly;
+static int phonet_net_id __read_mostly;
 
 static struct phonet_net *phonet_pernet(struct net *net)
 {