net: phy: smsc: enable edpd tunable support

Enable EDPD PHY tunable support for all drivers using
lan87xx_read_status.

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>