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/include/linux/fsl_devices.h b/include/linux/fsl_devices.h
index 1831b19..2cad5c6 100644
--- a/include/linux/fsl_devices.h
+++ b/include/linux/fsl_devices.h
@@ -50,7 +50,7 @@
 	u32	device_flags;
 	/* board specific information */
 	u32	board_flags;
-	u32	bus_id;
+	char	bus_id[MII_BUS_ID_SIZE];
 	u32	phy_id;
 	u8	mac_addr[6];
 	phy_interface_t interface;