net: dsa: remove ethtool_ops->set_sg

Remove set_sg from DSA slave ethtool_ops. Features inheritance looks
broken/not fully implemented anyway.
Signed-off-by: NMichał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/dsa/slave.c

@@ -288,7 +288,6 @@ static const struct ethtool_ops dsa_slave_ethtool_ops = {
 	.get_drvinfo		= dsa_slave_get_drvinfo,
 	.nway_reset		= dsa_slave_nway_reset,
 	.get_link		= dsa_slave_get_link,
-	.set_sg			= ethtool_op_set_sg,
 	.get_strings		= dsa_slave_get_strings,
 	.get_ethtool_stats	= dsa_slave_get_ethtool_stats,
 	.get_sset_count		= dsa_slave_get_sset_count,