Rework the PCI wake-up code so that it's easier to read without
changing the functionality.
Reviewed-by: NMatthew Garrett <mjg59@srcf.ucam.org>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>