drivers/net/wan/lapbether: Added needed_tailroom

The underlying Ethernet device may request necessary tailroom to be
allocated by setting needed_tailroom. This driver should also set
needed_tailroom to request the tailroom needed by the underlying
Ethernet device to be allocated.

Cc: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Cc: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: NXie He <xie.he.0141@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/wan/lapbether.c

@@ -340,6 +340,7 @@ static int lapbeth_new_device(struct net_device *dev)
 	 */
 	ndev->needed_headroom = -1 + 3 + 2 + dev->hard_header_len
 					   + dev->needed_headroom;
+	ndev->needed_tailroom = dev->needed_tailroom;
 
 	lapbeth = netdev_priv(ndev);
 	lapbeth->axdev = ndev;