eeepc-laptop: check wireless hotplug events

Before we mark the wireless device as unplugged, check PCI config space
to see whether the wireless device is really disabled (and vice versa).
This works around newer models which don't want the hotplug code, where
we end up disabling the wired network device.

My old 701 still works correctly with this.  I can also simulate an
afflicted model by changing the hardcoded PCI bus/slot number in the
driver, and it seems to work nicely (although it is a bit noisy).

In future this type of hotplug support will be implemented by the PCI
core.  The existing blacklist and the new warning message will be
removed at that point.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>