ACPICA: Add support for _LPD and _PRP methods.

This patch currently only affects acpihelp and iASL which are not shipped
in the Linux kernel.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>