ACPICA: Cleanup the global variables and update comments

ACPICA commit 8519ba376636565350c3fa0db5621c61d34c34b2

Mostly cleanup/reformatting. Some restructuring.

No functional change.

Link: https://github.com/acpica/acpica/commit/8519ba37


Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>