net: lan78xx: Allow for VLAN headers in timeout.

The frame abort timeout being set by lan78xx_set_rx_max_frame_length
didn't account for any VLAN headers, resulting in very low
throughput if used with tagged VLANs.
Use VLAN_ETH_HLEN instead of ETH_HLEN to correct for this.

See raspberrypi/linux#2458

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>

drivers/net/usb/lan78xx.c

@@ -2298,7 +2298,7 @@ static int lan78xx_change_mtu(struct net_device *netdev, int new_mtu)
 	if ((ll_mtu % dev->maxpacket) == 0)
 		return -EDOM;
 
-	ret = lan78xx_set_rx_max_frame_length(dev, new_mtu + ETH_HLEN);
+	ret = lan78xx_set_rx_max_frame_length(dev, new_mtu + VLAN_ETH_HLEN);
 
 	netdev->mtu = new_mtu;
 
@@ -2598,7 +2598,8 @@ static int lan78xx_reset(struct lan78xx_net *dev)
 	buf |= FCT_TX_CTL_EN_;
 	ret = lan78xx_write_reg(dev, FCT_TX_CTL, buf);
 
-	ret = lan78xx_set_rx_max_frame_length(dev, dev->net->mtu + ETH_HLEN);
+	ret = lan78xx_set_rx_max_frame_length(dev,
+					      dev->net->mtu + VLAN_ETH_HLEN);
 
 	ret = lan78xx_read_reg(dev, MAC_RX, &buf);
 	buf |= MAC_RX_RXEN_;