Depsgraph: Correct FPS debug print

It was printing "frame" time instead of FPS.

Other interesting thing to get solved is to solve "drop" in FPS
when there is an idle time in user input.

Current usecase is limited to observing FPS when there is a continuous
stream of events: for example, keep moving vertex in edit mode while
watching debug prints.

source/blender/depsgraph/intern/debug/deg_debug.cc

@@ -67,7 +67,7 @@ void DepsgraphDebug::end_graph_evaluation()
 
   const double graph_eval_end_time = PIL_check_seconds_timer();
   printf("Depsgraph updated in %f seconds.\n", graph_eval_end_time - graph_evaluation_start_time_);
-  printf("Depsgraph evaluation FPS: %f\n", fps_samples_.get_averaged());
+  printf("Depsgraph evaluation FPS: %f\n", 1.0f / fps_samples_.get_averaged());
 
   is_ever_evaluated = true;
 }