um: reject unsupported coalescing params

Set ethtool_ops->supported_coalesce_params to let
the core reject unsupported coalescing parameters.

This driver did not previously reject unsupported parameters.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/um/drivers/vector_kern.c

@@ -1508,6 +1508,7 @@ static int vector_set_coalesce(struct net_device *netdev,
 }
 
 static const struct ethtool_ops vector_net_ethtool_ops = {
+	.supported_coalesce_params = ETHTOOL_COALESCE_TX_USECS,
 	.get_drvinfo	= vector_net_get_drvinfo,
 	.get_link	= ethtool_op_get_link,
 	.get_ts_info	= ethtool_op_get_ts_info,