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/tg3.h b/drivers/net/tg3.h
index 6c7b5e3..be252ab 100644
--- a/drivers/net/tg3.h
+++ b/drivers/net/tg3.h
@@ -2556,7 +2556,7 @@
 	int				msi_cap;
 	int				pcix_cap;
 
-	struct mii_bus			mdio_bus;
+	struct mii_bus			*mdio_bus;
 	int				mdio_irq[PHY_MAX_ADDR];
 
 	/* PHY info */