If we point to a PHY node by phandle, that PHY might well be on a MDIO
bus that hasn't been scanned when we look for the PHY. Fortunately we
know exactly where to look for the PHY, so make sure to scan the bus
at the right address.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>