Merge branch 'acpica'

Merge branch 'acpica'

ACPICA update to upstream revision 20180531 (including an important
AML parser fix and updates related to IORT) and a change to start
responding to the "Windows 2017.2" _OSI string.

* acpica:
  ACPICA: Recognize the _OSI string "Windows 2017.2"
  ACPICA: Update version to 20180531
  ACPICA: Interpreter: Begin deprecation of Unload operator
  ACPICA: AML parser: attempt to continue loading table after error
  ACPICA: Debugger: Reduce verbosity for module-level code errors.
  ACPICA: AML Parser: Add debug option to dump parse trees
  ACPICA: Debugger: Add count of namespace nodes after namespace dump
  ACPICA: IORT: Add PMCG node supprt
  ACPICA: IORT: Update for revision D