ACPICA: Enable Scope change to root during module-level code execution.

Allows constructs like this:
    If (XXXX)
        Scope (\)
        ...

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>