gstframepositioner: fix operator magic number
In gst_frame_positioner_init, there was the magic number 1 when assigning the default value of the operator. Now it has the default value for the operator pulled from the compositor.
In gst_frame_positioner_init, there was the magic number 1 when assigning the default value of the operator. Now it has the default value for the operator pulled from the compositor.