ACPICA: ACPI 6.0/iASL: Add support for the External AML opcode

ACPICA commit 882892feeafe8b8e5be10463133405cd4f1309d9

Support for both the compiler and disassembler.
Also, the interpreter will ignore this opcode if it
is ever encountered (should not happen).
David Box.

Link: https://github.com/acpica/acpica/commit/882892fe


Signed-off-by: David E. Box <david.e.box@linux.intel.com>
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>