ACPI: thinkpad-acpi: cleanup bluetooth and wan for sysfs conversion

Prepare bluetooth and wan driver code to be more easily hooked into sysfs
helpers, by separating the procfs logic from the device attribute handling.

These changes also remove the entries from procfs on notebooks without the
bluetooth/wan hardware installed.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>