phylib: move to dynamic allocation of struct mii_bus

This patch introduces mdiobus_alloc() and mdiobus_free(), and
makes all mdio bus drivers use these functions to allocate their
struct mii_bus'es dynamically.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Andy Fleming <afleming@freescale.com>
diff --git a/drivers/net/macb.h b/drivers/net/macb.h
index 57b85ac..d3212f6 100644
--- a/drivers/net/macb.h
+++ b/drivers/net/macb.h
@@ -384,7 +384,7 @@
 
 	unsigned int		rx_pending, tx_pending;
 
-	struct mii_bus		mii_bus;
+	struct mii_bus		*mii_bus;
 	struct phy_device	*phy_dev;
 	unsigned int 		link;
 	unsigned int 		speed;