mac8390: fix build with NET_POLL_CONTROLLER

Fix the build for CONFIG_NET_POLL_CONTROLLER that I broke with
217cbfa8 ("mac8390: fix regression
caused during net_device_ops conversion").

Signed-off-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>