ACPI / PM: Do not apply ACPI_SUCCESS() to acpi_bus_get_device() result

Since the return value of acpi_bus_get_device() is not of type
acpi_status, ACPI_SUCCESS() should not be used for checking its
return value.  Fix that.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Mika Westerberg <mika.westerberg@linux.intel.com>