thinkpad-acpi: fix initialization error paths

Rework some subdriver init and exit handlers, in order to fix some
initialization error paths that were missing, or broken.

Hitting those bugs should be extremely rare in the real world, but should
that happen, thinkpad-acpi would fail to dealocate some resources and a
reboot might well be needed to be able to load the driver again.

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