net: dsa: ocelot: felix: utilize shared mscc-miim driver for indirect MDIO access

Switch to a shared MDIO access implementation by way of the mdio-mscc-miim
driver.

Signed-off-by: Colin Foster <colin.foster@in-advantage.com>
Tested-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>