ACPI: Advertise to BIOS in _OSC: _OST on _PPC changes

If the BIOS pokes the system-wide OSC bits to see if Linux
supports evaluating _OST after a _PPC change notification,
answer yes.

Also, fix an oversight where we neglected to set the OSC
bit advertising processor aggregator device support
when acpi-pad is compiled as a module.

Signed-off-by: Zhao Yakui <yakui.zhao@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>