Lenovo Yoga Book uses PWM2 for controlling keyboard backlight but this
device is hidden in the DSDT in Windows version of notebook (if OSID == 1).

Make this device always present for this notebook.
Signed-off-by: Yauhen Kharuzhy <jekhor@gmail.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>