PCI PM: Fix hibernation breakage on EeePC 701

Hibernation breaks on EeePC 701 as a result of attempting to put one
of its (driverless) devices into a low power state.  Avoid that by
not attepmting to power manage driverless devices during hibernation.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Reported-and-tested-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>

drivers/pci/pci-driver.c

@@ -669,7 +669,10 @@ static int pci_pm_poweroff(struct device *dev)
 	if (pci_has_legacy_pm_support(pci_dev))
 		return pci_legacy_suspend(dev, PMSG_HIBERNATE);
 
-	if (drv && drv->pm && drv->pm->poweroff) {
+	if (!drv || !drv->pm)
+		return 0;
+
+	if (drv->pm->poweroff) {
 		error = drv->pm->poweroff(dev);
 		suspend_report_result(drv->pm->poweroff, error);
 	}