librbd: Remove unneeded set_event_notify

Since xlist clear method invoked below is enough to disassociate the xlist
item from the xlist, so the remove_myself() call in the destructor is safe
to invoke since it's already been removed from the list.

Signed-off-by: Haomai Wang <haomai@xsky.com>

src/librbd/ImageCtx.cc

@@ -816,16 +816,9 @@ class ThreadPoolSingleton : public ThreadPool {
     Mutex::Locker l(completed_reqs_lock);
     ldout(cct, 10) << "clear pending AioCompletion: count="
                    << completed_reqs.size() << dendl;
-
-    for (xlist<AioCompletion*>::iterator it = completed_reqs.begin();
-         !it.end(); ++it) {
-      ldout(cct, 10) << "clear pending AioCompletion: " << *it << dendl;
-      (*it)->set_event_notify(false);
-    }
     completed_reqs.clear();
   }
 
-
   bool ImageCtx::_filter_metadata_confs(const string &prefix, map<string, bool> &configs,
                                         map<string, bufferlist> &pairs, map<string, bufferlist> *res) {
     size_t conf_prefix_len = prefix.size();