PCI / PM: Do not resume any devices in pci_pm_prepare()

It should not be necessary to resume devices with ignore_children set
in pci_pm_prepare(), because they should be resumed explicitly by
their children drivers during suspend if need be and they will be
resumed by pci_pm_suspend() after that anyway, so avoid doing that.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/pci/pci-driver.c

@@ -680,13 +680,6 @@ static int pci_pm_prepare(struct device *dev)
 {
 	struct device_driver *drv = dev->driver;
 
-	/*
-	 * Devices having power.ignore_children set may still be necessary for
-	 * suspending their children in the next phase of device suspend.
-	 */
-	if (dev->power.ignore_children)
-		pm_runtime_resume(dev);
-
 	if (drv && drv->pm && drv->pm->prepare) {
 		int error = drv->pm->prepare(dev);
 		if (error)