avfilter/vf_uspp: Fix leak of qp-table on error

Fixes Coverity issue #1473500.

Reviewed-by: Michael Niedermayer <michael@niedermayer.cc>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavfilter/vf_uspp.c

@@ -425,6 +425,8 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
                 out = ff_get_video_buffer(outlink, aligned_w, aligned_h);
                 if (!out) {
                     av_frame_free(&in);
+                    if (qp_table != uspp->non_b_qp_table)
+                        av_free(qp_table);
                     return AVERROR(ENOMEM);
                 }
                 av_frame_copy_props(out, in);