Rename property enums from ARG_ to PROP_
Rename property enums from ARG_ to PROP_

Property enum items should be named PROP_ for consistency and readability.

GStreamer/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,pexip/gst-plugins-good