sony-laptop: enumerate rfkill devices using SN06

SN06 makes sure we get back a longer buffer which seems to be necessary
going forward as the SNC devices describes more and more devices (or
features more precisely). Moreover SN06 should be called with only the
descriptor offset to make sure we hit the rfkill controlling function
(F124 or F135) with a 0 argument to get a full list of features.

Signed-off-by: Mattia Dongili <malattia@linux.it>
Tested-by: Miguel Rodríguez Pérez <miguelrp@gmail.com>
Signed-off-by: Len Brown <len.brown@intel.com>