AR8035 recently gained MDIX support. The same functions will work for
the AR8031/33 PHY. We just need to add the at803x_config_aneg()
callback.

This was tested on a Kontron sl28 board.
Signed-off-by: Michael Walle <michael@walle.cc>
Signed-off-by: David S. Miller <davem@davemloft.net>