sky2: Enable/disable WOL per hardware device

Y2_HW_WOL_ON/Y2_HW_WOL_OFF should be set and cleared per chip,
not per port.  On dual port cards, Y2_HW_WOL_ON should be
enabled if either sky2 port has WOL enabled.

Found while reviewing code for a WOL regression, though this is
probably not the cause of the regression.

Signed-off-by: Mike McCormack <mikem@ring3k.org>
Signed-off-by: David S. Miller <davem@davemloft.net>