ACPI: processor: unify arch_acpi_processor_init_pdc

The x86 and ia64 implementations of arch_acpi_processor_init_pdc()
are almost exactly the same. The only difference is in what bits
they set in obj_list buffer.

Combine the boilerplate memory management code, and leave the
arch-specific bit twiddling in separate implementations.

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>