tools/power/acpi: Add userspace AML interface support

This patch adds a userspace tool to access Linux kernel AML debugger
interface.

Tow modes are supported by this tool:
1. Interactive: Users are able to launch a debugging shell to talk with
   in-kernel AML debugger.
   Note that it's user duty to ensure kernel runtime integrity by using
   this debugging tool:
   A. Some control methods evaluated by the users may result in kernel
      panics if those control methods shouldn't be evaluated by the OSPMs
      according to the current BIOS/OS configurations.
   B. Currently if a single stepping evaluation couldn't run to an end,
      then the synchronization primitives acquired by the evaluation may
      block normal OSPM control method evaluations.
2. Batch: Users are able to execute debugger commands in a script.
   Note that in addition to the above duties, it's user duty to ensure
   script runtime integrity by using this debugging tool in this mode:
   C. Currently only those commands that are not used for single stepping
      are suitable to be used in this mode.
   D. If the execution of the command may cause a failure that could result
      in an endless kernel execution, the execution of the script may also
      get blocked.
To exit the utility, currently "exit/quit" commands are recommended, but
ctrl-C" can also be used.

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