ixgbe: Not allow 8259x unsupported wol options change from ethtool

Wake-on-lan is currently only supported by 82599 KX4 devices, in all
other cases return a proper value from ixgbe_wol_exclusion function call.
Otherwise from ethtool we will be able to change wol options of
unsupported 8259x devices.

Signed-off-by: Mallikarjuna R Chilakala <mallikarjuna.chilakala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ixgbe/ixgbe_ethtool.c

@@ -1830,7 +1830,6 @@ static int ixgbe_wol_exclusion(struct ixgbe_adapter *adapter,
 		break;
 	default:
 		wol->supported = 0;
-		retval = 0;
 	}
 
 	return retval;