dpaa2-eth: add basic devlink support

Add basic support in dpaa2-eth for devlink. For the moment, just
register the device with devlink, add the corresponding devlink port and
implement the .info_get() callback.

Signed-off-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>