Implemented a full bytewise compare to determine if a table load
request is attempting to load a duplicate table. The compare is
performed if the table signatures and table lengths match. This
will allow different tables with the same OEM Table ID and
revision to be loaded.

Although the BIOS is technically violating the ACPI spec when
this happens -- it does happen -- so Linux must handle it.

Signed-off-by: Robert Moore <robert.moore@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>