3c59x: Use device_set_wakeup_enable

Since dev->power.should_wakeup bit is used by the PCI core to
decide whether the device should wake up the system from sleep
states, set this bit by calling device_set_wakeup_enable().

This restores proper WOL for the 3c59x driver.

Reported-and-tested-by: Graeme Wilford <gwilford@gmail.com>
Reported-by: Gunnar Degnbol <degnbol@danbbs.dk>
Signed-off-by: Steffen Klassert <klassert@mathematik.tu-chemnitz.de>
Signed-off-by: David S. Miller <davem@davemloft.net>