Fix warnings about unused private fields

avfaudioinputselectorcontrol.h:68:23: warning: private field 'm_service' is not used [-Wunused-private-field]

Change-Id: I5722a2d1bf592862af3a4d36554419a653662892
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>

src/plugins/avfoundation/camera/avfaudioinputselectorcontrol.h

@@ -65,8 +65,6 @@ public:
     AVCaptureDevice *createCaptureDevice();
 
 private:
-    AVFCameraService *m_service;
-
     QString m_activeInput;
     bool m_dirty;
     QString m_defaultDevice;