Various improvements for configuring the MPC5200 MII link from the
device tree:
* Look for 'current-speed' property for fixed speed MII links
* Look for 'fsl,7-wire-mode' property for boards using the 7 wire mode
* move definition of private data structure out of the header file
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>
Acked-by: NWolfgang Grandegger <wg@grandegger.com>