phy: Add API for {un}registering an mdio device to a bus.

Rather than have drivers directly manipulate the mii_bus structure,
provide and API for registering and unregistering devices on an MDIO
bus, and performing lookups.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/ethoc.c b/drivers/net/ethernet/ethoc.c
index c028b29..62fa136 100644
--- a/drivers/net/ethernet/ethoc.c
+++ b/drivers/net/ethernet/ethoc.c
@@ -678,7 +678,7 @@
 	int err;
 
 	if (priv->phy_id != -1)
-		phy = priv->mdio->phy_map[priv->phy_id];
+		phy = mdiobus_get_phy(priv->mdio, priv->phy_id);
 	else
 		phy = phy_find_first(priv->mdio);
 
@@ -766,7 +766,7 @@
 		if (mdio->phy_id >= PHY_MAX_ADDR)
 			return -ERANGE;
 
-		phy = priv->mdio->phy_map[mdio->phy_id];
+		phy = mdiobus_get_phy(priv->mdio, mdio->phy_id);
 		if (!phy)
 			return -ENODEV;
 	} else {