osssrc: remove unnecessary NULL check before g_free()
osssrc: remove unnecessary NULL check before g_free()

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