ethtool: Account for hw_features in netlink interface

ethtool-netlink ignores dev->hw_features and may confuse the drivers by
asking them to enable features not in the hw_features bitmask. For
example:

1. ethtool -k eth0
   tls-hw-tx-offload: off [fixed]
2. ethtool -K eth0 tls-hw-tx-offload on
   tls-hw-tx-offload: on
3. ethtool -k eth0
   tls-hw-tx-offload: on [fixed]

Fitler out dev->hw_features from req_wanted to fix it and to resemble
the legacy ethtool behavior.

Fixes: 0980bfcd ("ethtool: set netdev features with FEATURES_SET request")
Signed-off-by: Maxim Mikityanskiy <maximmi@mellanox.com>
Reviewed-by: Michal Kubecek <mkubecek@suse.cz>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ethtool/features.c

@@ -273,7 +273,8 @@ int ethnl_set_features(struct sk_buff *skb, struct genl_info *info)
 		goto out_rtnl;
 	}
 
-	dev->wanted_features = ethnl_bitmap_to_features(req_wanted);
+	dev->wanted_features &= ~dev->hw_features;
+	dev->wanted_features |= ethnl_bitmap_to_features(req_wanted) & dev->hw_features;
 	__netdev_update_features(dev);
 	ethnl_features_to_bitmap(new_active, dev->features);
 	mod = !bitmap_equal(old_active, new_active, NETDEV_FEATURE_COUNT);