ACPI / PM: Support D3 COLD device in old BIOS for ZPODD

D3cold is only regarded as valid if the "_PR3" object is
present for the given device after the commit 20dacb7
("ACPI/PM: Rework device power management to follow ACPI 6").

But some old BIOS only defined "_PS3" for the D3COLD device,
such as ZPODD device. And old kernel also believes the device with
"_PS3" is a D3COLD device.

So, add some logics for supporting D3 COLD device with old BIOS
which is compatible with earlier ACPI spec and kernel behavior.

Link: http://marc.info/?l=linux-acpi&m=144946938709759&w=2
Signed-off-by: Ken Xue <Ken.Xue@amd.com>
Reported-and-tested-by: Gang Long <Gang.Long@amd.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/acpi/acpi_bus.h

@@ -631,7 +631,9 @@ static inline bool acpi_device_can_wakeup(struct acpi_device *adev)
 
 static inline bool acpi_device_can_poweroff(struct acpi_device *adev)
 {
-	return adev->power.states[ACPI_STATE_D3_COLD].flags.valid;
+	return adev->power.states[ACPI_STATE_D3_COLD].flags.valid ||
+		((acpi_gbl_FADT.header.revision < 6) &&
+		adev->power.states[ACPI_STATE_D3_HOT].flags.explicit_set);
 }
 
 #else	/* CONFIG_ACPI */