atm: convert mpc device to using netdev_ops

This converts the mpc device to using new netdevice_ops.
Compile tested only, needs more than usual review since
device was swaping pointers around etc.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Acked-by: Chas Williams <chas@cmf.nrl.navy.mil>
Signed-off-by: David S. Miller <davem@davemloft.net>