net/fec_mpc52xx: Migrate to net_device_ops.

Since not using net_device_ops gets you shunned out the cool crowd,
this patch modifies the fec_mpc52xx Ethernet driver to provide the
management hooks via a struct net_device_ops.

Reported-by: Henk Stegeman <henk.stegeman@gmail.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>