drivers: net: sun4i-emac: select MDIO_SUN4I

The EMAC driver can't work without its associated PHY driver. Reflect
this in the Kconfig options by selecting it.
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/allwinner/Kconfig

@@ -27,6 +27,7 @@ config SUN4I_EMAC
 	select CRC32
 	select MII
 	select PHYLIB
+	select MDIO_SUN4I
         ---help---
           Support for Allwinner A10 EMAC ethernet driver.