Implement wireless like hotplug handling (code stolen from eeepc-laptop).

Reminder: on some models rfkill is implemented by logically unplugging the
wireless card from the PCI bus. Despite sending ACPI notifications, this does
not appear to be implemented using standard ACPI hotplug - nor does the
firmware provide the _OSC method required to support native PCIe hotplug.
The only sensible choice appears to be to handle the hotplugging directly in
the platform driver.
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Signed-off-by: Matthew Garrett <mjg@redhat.com>