eeepc-laptop: Register as a pci-hotplug device

The eee contains a logically (but not physically) hotpluggable PCIe slot.
Currently this is handled by adding or removing the PCI device in response
to rfkill events, but if a user has forced pciehp to bind to it (with the
force=1 argument) then both drivers will try to handle the event and
hilarity (in the form of oopses) will ensue. This can be avoided by having
eee-laptop register the slot as a hotplug slot. Only one of pciehp and
eee-laptop will successfully register this, avoiding the problem.

Signed-off-by: Matthew Garrett <mjg@redhat.com>
Signed-off-by: Corentin Chary <corentincj@iksaif.net>
Tested-by: Darren Salt <linux@youmustbejoking.demon.co.uk>
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Len Brown <len.brown@intel.com>