ACPICA: Cleanup for internal Reference Object

Fix some sloppiness in the Reference object. No longer use AML
opcodes to differentiate the types, introduce new reference
Class. Cleanup the debug output code.

Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>