netxen: convert to net_device_ops

Convert driver to new net_device_ops. Compile tested only.
Had to do some refactoring on multicast_list.
Fix ethtool restart to propogate error code.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>