ACPI: Add D3 cold state

_SxW returns an Integer containing the lowest D-state supported in state
Sx. If OSPM has not indicated that it supports _PR3, then the value “3”
corresponds to D3.  If it has indicated _PR3 support, the value “3”
represents D3hot and the value “4” represents D3cold.

Linux does set _OSC._PR3, so we should fix it to expect that _SxW can
return 4.

Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Len Brown <len.brown@intel.com>

drivers/pci/pci-acpi.c

@@ -195,6 +195,8 @@ static pci_power_t acpi_pci_choose_state(struct pci_dev *pdev)
 		return PCI_D2;
 	case ACPI_STATE_D3:
 		return PCI_D3hot;
+	case ACPI_STATE_D3_COLD:
+		return PCI_D3cold;
 	}
 	return PCI_POWER_ERROR;
 }