r8169: runtime resume before shutdown.

r8169: runtime resume before shutdown.

With runtime PM, if the ethernet cable is disconnected, the device is
transitioned to D3 state to conserve energy. If the system is shutdown
in this state, any register accesses in rtl_shutdown are dropped on
the floor. As the device was programmed by .runtime_suspend() to wake
on link changes, it is thus brought back up as soon as the link recovers.

Resuming every suspended device through the driver core would slow things
down and it is not clear how many devices really need it now.

Original report and D0 transition patch by Sameer Nanda. Patch has been
changed to comply with advices by Rafael J. Wysocki and the PM folks.

Reported-by: Sameer Nanda <snanda@chromium.org>
Signed-off-by: Francois Romieu <romieu@fr.zoreil.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Hayes Wang <hayeswang@realtek.com>
Cc: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: David S. Miller <davem@davemloft.net>