atmel: fix netdev ops conversion

sparse says:

drivers/net/wireless/atmel.c:1501:3: warning: Initializer entry defined twice
drivers/net/wireless/atmel.c:1505:3:   also defined here

and it's correct; atmel has its own ndo_change_mtu and
shouldn't use eth_change_mtu.
Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wireless/atmel.c

@@ -1502,7 +1502,6 @@ static const struct net_device_ops atmel_netdev_ops = {
 	.ndo_set_mac_address 	= atmel_set_mac_address,
 	.ndo_start_xmit 	= start_tx,
 	.ndo_do_ioctl 		= atmel_ioctl,
-	.ndo_change_mtu		= eth_change_mtu,
 	.ndo_validate_addr	= eth_validate_addr,
 };