kernel/timer: Add missing base object

src/core/hle/kernel/timer.h

@@ -115,6 +115,7 @@ private:
     friend class boost::serialization::access;
     template <class Archive>
     void serialize(Archive& ar, const unsigned int file_version) {
+        ar& boost::serialization::base_object<WaitObject>(*this);
         ar& reset_type;
         ar& initial_delay;
         ar& interval_delay;