Common: don't call OnConfigChanged() unless it has actually changed

DualShock UDP Client is the only place in the code that assumed OnConfigChanged()
is called at least once on startup or it won't load up the setting, so I took care of that

Source/Core/InputCommon/ControllerInterface/DualShockUDPClient/DualShockUDPClient.cpp

@@ -381,7 +381,9 @@ void Init()
     Config::SetBase(Settings::SERVER_PORT, 0);
   }
 
+  // It would be much better to unbind from this callback on DeInit but it's not possible as of now
   Config::AddConfigChangedCallback(ConfigChanged);
+  ConfigChanged();  // Call it immediately to load settings
 }
 
 void PopulateDevices()