eeepc-laptop: fix rfkill memory leak on unload

rfkill_unregister() should always be followed by rfkill_destroy()

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>