ACPI processor: remove processor throttling control procfs I/F

Remove deprecated ACPI process procfs I/F for throttling control.

This is because the t-state control should only be done in kernel,
when system is in a overheating state.

Now users can only change the processor t-state indirectly,
by poking the cooling device sysfs I/F of the processor.

Signed-off-by: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>