eeepc-laptop: allow rfkill hotplug to work on the 900A model

The 900A provides hotplug notifications on a different ACPI object to
other models.

Reported-by: Trevor <trevor.chart@gmail.com>
Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Len Brown <len.brown@intel.com>