small changes for better readability

source/RobotAPI/libraries/armem/server/ltm/processors/filter/frequencyFilter/FrequencyFilter.cpp

@@ -36,9 +36,9 @@ namespace armarx::armem::server::ltm::processor::filter
 
                     if(instances_accepted){
                         lastTime = current;
-                        stats.accepted += 1;
+                        this->stats.accepted += 1;
                     } else {
-                        stats.rejected += 1;
+                        this->stats.rejected += 1;
                     }
                     return instances_accepted;
     }