Fix log_stats

It wasn't deregistering

Change-Id: I0ce4889d271d1ec2ae269b55a0134625e9c73363
diff --git a/aos/events/logging/log_stats.cc b/aos/events/logging/log_stats.cc
index 47f3c5c..a2d8184 100644
--- a/aos/events/logging/log_stats.cc
+++ b/aos/events/logging/log_stats.cc
@@ -86,6 +86,7 @@
       for (const aos::Node *node : reader.Nodes()) {
         LOG(INFO) << "  " << node->name()->string_view();
       }
+      reader.Deregister();
       return 1;
     } else {
       node = aos::configuration::GetNode(reader.configuration(), FLAGS_node);