ACPI: processor: finish unifying arch_acpi_processor_init_pdc()

The only thing arch-specific about calling _PDC is what bits get
set in the input obj_list buffer.

There's no need for several levels of indirection to twiddle those
bits. Additionally, since we're just messing around with a buffer,
we can simplify the interface; no need to pass around the entire
struct acpi_processor * just to get at the buffer.

Cc: Tony Luck <tony.luck@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Alex Chiang <achiang@hp.com>
Signed-off-by: Len Brown <len.brown@intel.com>