The methods to read from / write to MII registers had an address argument to
allow specifying the PHY to communicate with. However, only a single PHY is
available on all boards supported and the driver is not able to operate with
multiple PHYs anyway - thus, drop this parameter for ease of use.
This fixes a bug in the _get_link_status() function, which used hard coded the
address 0; which might not be correct for all boards.
0e43c927b1