ACPI: thinkpad-acpi: spring cleanup part 2

Move most subdriver-related stuff imported from the header file closer to
their subdriver code.  Also, delete unneeded forward declarations.
Signed-off-by: NHenrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: NLen Brown <len.brown@intel.com>