Fix missing Deregister in log_cat

Change-Id: Id783f10bbd9b0e11ad9a6aa8b13d01bdafb70019
diff --git a/aos/events/logging/log_cat.cc b/aos/events/logging/log_cat.cc
index c77aa46..b31bba0 100644
--- a/aos/events/logging/log_cat.cc
+++ b/aos/events/logging/log_cat.cc
@@ -224,5 +224,7 @@
 
   event_loop_factory.Run();
 
+  reader.Deregister();
+
   return 0;
 }