deinterlace: Implement reconfiguration a bit better
deinterlace: Implement reconfiguration a bit better

And e.g. consider reconfiguration caused by RECONFIGURE events too.

https://bugzilla.gnome.org/show_bug.cgi?id=720388

pexip/gst-plugins-good,hizukiayaka/gst-plugins-good,pexip/gst-plugins-good,hizukiayaka/gst-plugins-good,stfl/gst-plugins-good,stfl/gst-plugins-good,GStreamer/gst-plugins-good,hizukiayaka/gst-plugins-good,StreamUtils/gst-plugins-good,GStreamer/gst-plugins-good,GStreamer/gst-plugins-good,GrokImageCompression/gst-plugins-good,Kurento/gst-plugins-good,pexip/gst-plugins-good,pexip/gst-plugins-good,stfl/gst-plugins-good,Kurento/gst-plugins-good,Kurento/gst-plugins-good,GrokImageCompression/gst-plugins-good,stfl/gst-plugins-good,StreamUtils/gst-plugins-good,GStreamer/gst-plugins-good,GrokImageCompression/gst-plugins-good,Kurento/gst-plugins-good,hizukiayaka/gst-plugins-good,pexip/gst-plugins-good,StreamUtils/gst-plugins-good,Kurento/gst-plugins-good,GrokImageCompression/gst-plugins-good,StreamUtils/gst-plugins-good