ACPI / PM: Add function for device power state initialization

Add function acpi_bus_init_power() for getting the initial power
state of an ACPI device and reference counting its power resources
as appropriate.

Make acpi_bus_get_power_flags() use the new function instead of
acpi_bus_get_power() that updates device->power.state without
reference counting the device's power resources.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/acpi/internal.h b/drivers/acpi/internal.h
index 433a8ee..7493e6c 100644
--- a/drivers/acpi/internal.h
+++ b/drivers/acpi/internal.h
@@ -44,6 +44,7 @@
 int acpi_power_get_inferred_state(struct acpi_device *device, int *state);
 int acpi_power_on_resources(struct acpi_device *device, int state);
 int acpi_power_transition(struct acpi_device *device, int state);
+int acpi_bus_init_power(struct acpi_device *device);
 extern int acpi_power_nocheck;
 
 int acpi_wakeup_device_init(void);