net: phy: smsc: clear edpd_enable if interrupt mode is used

Clear edpd_enable if interupt mode is used, this avoids
having to check for PHY_POLL multiple times.

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>