avformat/imf_cpl: Check the right variable

Fixes Coverity issue #1512407.

Reviewed-by: Pierre-Anthony Lemieux <pal@sandflow.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavformat/imf_cpl.c

@@ -625,7 +625,7 @@ static int fill_virtual_tracks(xmlNodePtr cpl_element, FFIMFCPL *cpl)
         av_log(NULL, AV_LOG_DEBUG, "Processing IMF CPL Segment\n");
 
         sequence_list_elem = ff_imf_xml_get_child_element_by_name(segment_elem, "SequenceList");
-        if (!segment_list_elem)
+        if (!sequence_list_elem)
             continue;
 
         sequence_elem = xmlFirstElementChild(sequence_list_elem);