don't return an error from unimplemented functions
don't return an error from unimplemented functions

sledges/gst-droid,mlehtima/gst-droid,sledges/gst-droid,foolab/gst-droid,sledges/gst-droid,sailfishos/gst-droid,foolab/gst-droid,mlehtima/gst-droid