ACPI / x86: Make PWM2 device always present at Lenovo Yoga Book

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>