Switch mv643xx_eth from using drivers/net/mii.c to using phylib.

Since the mv643xx_eth hardware does all the link state handling and
PHY polling, the driver will use phylib in the "Doing it all yourself"
mode described in the phylib documentation.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Andy Fleming <afleming@freescale.com>