So far rpm doesn't cover cases like unused ports which are never
brought up. If they are active at probe time they remain in this state.
Included in this patch:

- Let the idle notification check whether we can suspend and let it
  schedule the suspend. This way we don't need to have calls to
  pm_schedule_suspend in different places.

- At the end of rtl_open and rtl_init_one send an idle notification
  to allow suspending if the link is down. If a cable is plugged in
  aneg is finished before the suspend timer expires and the suspend
  request is cancelled.

- Change rtl8169_runtime_suspend to power down the chip if the
  interface is down.

Successfully tested on a RTL8168evl (mac version 34).
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>