ACPICA: Fixed a problem with Index Fields where the Index register was incorrectly limited to a maximum of 32 bits

Now any size may be used.
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Alexey Starikovskiy <astarikovskiy@suse.de>
Signed-off-by: Len Brown <len.brown@intel.com>