asus-wmi: move WAPF variable into quirks_entry

Some models work better with different values of wapf, so move the
variable into quriks_entry to make it more easy to give a specific
value to different models.

Based on original patch from AceLan Kao <acelan.kao@canonical.com>

Cc: AceLan Kao <acelan.kao@canonical.com>
Signed-off-by: Corentin Chary <corentin.chary@gmail.com>
Signed-off-by: Matthew Garrett <mjg@redhat.com>