NET: asix: fix ethtool -e for AX88178 USB dongle

"ethtool -e ethX" dumps EEPROM data. Patch sets EEPROM length for device.
Ethtool works alot better when the kernel believes the length is > 0.

From: Allan Chou <allan@asix.com.tw>
Signed-off-by: Grant Grundler <grundler@chromium.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/asix.c

@@ -1397,6 +1397,9 @@ static int ax88178_bind(struct usbnet *dev, struct usb_interface *intf)
 	int ret;
 	u8 buf[ETH_ALEN];
 	u32 phyid;
+	struct asix_data *data = (struct asix_data *)&dev->data;
+
+	data->eeprom_len = AX88772_EEPROM_LEN;
 
 	usbnet_get_endpoints(dev,intf);