3c59x: Rework suspend and resume

As noticed by Alan Stern, there is still one issue with the driver:
we disable PCI IRQ on suspend, but other devices on the same IRQ
line might still need the IRQ enabled to suspend properly.

Nowadays, PCI core handles all power management work by itself, with
one condition though: if we use dev_pm_ops. So, rework the driver to
only quiesce 3c59x internal logic on suspend, while PCI core will
manage PCI device power state with IRQs disabled.

Suggested-by: Rafael J. Wysocki <rjw@sisk.pl>
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>