tcp: don't require root to read tcp_metrics

commit d23ff701 (tcp: add generic netlink support for tcp_metrics) introduced
netlink support for the new tcp_metrics, however it restricted getting of
tcp_metrics to root user only. This is a change from how these values could
have been fetched when in the old route cache. Unless there's a legitimate
reason to restrict the reading of these values it would be better if normal
users could fetch them.

Cc: Julian Anastasov <ja@ssi.bg>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: NDebabrata Banerjee <dbanerje@akamai.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_metrics.c

@@ -1093,7 +1093,6 @@ static const struct genl_ops tcp_metrics_nl_ops[] = {
 		.doit = tcp_metrics_nl_cmd_get,
 		.dumpit = tcp_metrics_nl_dump,
 		.policy = tcp_metrics_nl_policy,
-		.flags = GENL_ADMIN_PERM,
 	},
 	{
 		.cmd = TCP_METRICS_CMD_DEL,