sctpassociation: Fix flag checking
sctpassociation: Fix flag checking

Closes #46.

ford-prefect/openwebrtc-gst-plugins,ford-prefect/openwebrtc-gst-plugins,EricssonResearch/openwebrtc-gst-plugins,sancane/openwebrtc-gst-plugins,ford-prefect/openwebrtc-gst-plugins,EricssonResearch/openwebrtc-gst-plugins,sancane/openwebrtc-gst-plugins,ford-prefect/openwebrtc-gst-plugins,EricssonResearch/openwebrtc-gst-plugins,sancane/openwebrtc-gst-plugins