netdev: restore MTU change operation

alloc_etherdev() used to install a default implementation of this
operation, but it must now be explicitly installed in struct
net_device_ops.

Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/usb/kaweth.c

@@ -999,6 +999,7 @@ static const struct net_device_ops kaweth_netdev_ops = {
 	.ndo_tx_timeout =		kaweth_tx_timeout,
 	.ndo_set_multicast_list =	kaweth_set_rx_mode,
 	.ndo_get_stats =		kaweth_netdev_stats,
+	.ndo_change_mtu =		eth_change_mtu,
 	.ndo_set_mac_address =		eth_mac_addr,
 	.ndo_validate_addr =		eth_validate_addr,
 };