net: ethtool: require drivers to set supported_coalesce_params

Now that all in-tree drivers have been updated we can
make the supported_coalesce_params mandatory.

To save debugging time in case some driver was missed
(or is out of tree) add a warning when netdev is registered
with set_coalesce but without supported_coalesce_params.

Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/ethtool.h

diff --git a/include/linux/ethtool.h b/include/linux/ethtool.h
index be355f3..c1d379bf 100644
--- a/include/linux/ethtool.h
+++ b/include/linux/ethtool.h
@@ -458,6 +458,8 @@ struct ethtool_ops {
 					 struct ethtool_stats *, u64 *);
 };
 
+int ethtool_check_ops(const struct ethtool_ops *ops);
+
 struct ethtool_rx_flow_rule {
 	struct flow_rule	*rule;
 	unsigned long		priv[0];