phy: Change mii_bus id field to a string

Having the id field be an int was making more complex bus topologies
excessively difficult.  For now, just convert it to a string, and
change all instances of "bus->id = val" to
snprintf(id, MII_BUS_ID_LEN, "%x", val).

Signed-off-by: Andy Fleming <afleming@freescale.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
diff --git a/drivers/net/gianfar_mii.c b/drivers/net/gianfar_mii.c
index 2432762..b889892 100644
--- a/drivers/net/gianfar_mii.c
+++ b/drivers/net/gianfar_mii.c
@@ -173,7 +173,7 @@
 	new_bus->read = &gfar_mdio_read,
 	new_bus->write = &gfar_mdio_write,
 	new_bus->reset = &gfar_mdio_reset,
-	new_bus->id = pdev->id;
+	snprintf(new_bus->id, MII_BUS_ID_SIZE, "%x", pdev->id);
 
 	pdata = (struct gianfar_mdio_data *)pdev->dev.platform_data;