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>
diff --git a/drivers/acpi/bus.c b/drivers/acpi/bus.c
index 9749980..d1e06c1 100644
--- a/drivers/acpi/bus.c
+++ b/drivers/acpi/bus.c
@@ -227,7 +227,7 @@
 	acpi_status status = AE_OK;
 	char object_name[5] = { '_', 'P', 'S', '0' + state, '\0' };
 
-	if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3))
+	if (!device || (state < ACPI_STATE_D0) || (state > ACPI_STATE_D3_COLD))
 		return -EINVAL;
 
 	/* Make sure this is a valid target state */