OpenNI2: prevent failure of setVideoMode() call with invalid parameters

Not all parameters are specified for openni::VideoMode, so
"selected" mode can be unsupported for device.
Replace default VideoMode constructor to result of getVideoMode() call.

modules/videoio/src/cap_openni2.cpp

@@ -646,7 +646,7 @@ bool CvCapture_OpenNI2::setImageGeneratorProperty(int propIdx, double propValue)
         {
         case CV_CAP_PROP_OPENNI_OUTPUT_MODE :
         {
-            openni::VideoMode mode;
+            openni::VideoMode mode = color.getVideoMode();
 
             switch( cvRound(propValue) )
             {