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>
diff --git a/drivers/net/usb/pegasus.c b/drivers/net/usb/pegasus.c
index 9bea2af..631d269a 100644
--- a/drivers/net/usb/pegasus.c
+++ b/drivers/net/usb/pegasus.c
@@ -1493,6 +1493,7 @@
 	.ndo_set_multicast_list =	pegasus_set_multicast,
 	.ndo_get_stats =		pegasus_netdev_stats,
 	.ndo_tx_timeout =		pegasus_tx_timeout,
+	.ndo_change_mtu =		eth_change_mtu,
 	.ndo_set_mac_address =		eth_mac_addr,
 	.ndo_validate_addr =		eth_validate_addr,
 };