ACPICA: Report error if method creates 2 objects with the same name

Fixed a regression where an error was no
longer emitted if a control method attempts to create 2
objects of the same name. This previously and now returns
AE_ALREADY_EXISTS. When this exception occurs, it invokes
the mechanism that will dynamically serialize the control
method to possible prevent future errors. (BZ 440)

Signed-off-by: Alexey Starikovskiy <alexey.y.starikovskiy@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>