net: ethernet: fec_mpc52xx: move to new ethtool api {get|set}_link_ksettings

The ethtool api {get|set}_settings is deprecated.
We move the fec_mpc52xx driver to new api {get|set}_link_ksettings.

Signed-off-by: Philippe Reynes <tremyfr@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>