asus-nb-wmi: Add wapf4 quirk for the X550CL

As reported here: https://bugs.launchpad.net/bugs/1277959


the X550CL needs wapf=4 too.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>