PCI/PM: Allow PCI devices to be put into D3cold during system suspend

Commit 448bd857 ("PCI/PM: add PCIe runtime D3cold support") added a
check to prevent PCI devices from being put into D3cold during system
suspend without giving any particular reason.

Also the check isn't really necessary, because acpi_pci_set_power_state()
maps PCI_D3hot to ACPI_STATE_D3_COLD anyway.
Signed-off-by: NRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: NBjorn Helgaas <bhelgaas@google.com>

drivers/pci/pci.c

@@ -1907,10 +1907,6 @@ int pci_prepare_to_sleep(struct pci_dev *dev)
 	if (target_state == PCI_POWER_ERROR)
 		return -EIO;
 
-	/* D3cold during system suspend/hibernate is not supported */
-	if (target_state > PCI_D3hot)
-		target_state = PCI_D3hot;
-
 	pci_enable_wake(dev, target_state, device_may_wakeup(&dev->dev));
 
 	error = pci_set_power_state(dev, target_state);