ACPICA: Update for "orphan" embedded controller _REG method support

ACPICA: Update for "orphan" embedded controller _REG method support

This refers to _REG methods under the EC device that have no
corresponding operation region. This is allowed by the ACPI
specification. This update removes a dependency on having an
ECDT table, and will execute an orphan _REG method as long as
the handler for the EC is installed at the EC device node (not
the namespace root).  Rui Zhang (original update), Bob Moore
(update/integrate).

Signed-off-by: Zhang Rui <[email protected]>
Signed-off-by: Bob Moore <[email protected]>
Signed-off-by: Lv Zheng <[email protected]>
Acked-by: Len Brown <[email protected]>
Signed-off-by: Rafael J. Wysocki <[email protected]>