avcodec/vc2enc: Remove superfluous error message

ff_get_encode_buffer() already emits an error message of its own.
While just at it, also check for ret < 0 instead of just ret != 0.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>

libavcodec/vc2enc.c

@@ -918,10 +918,8 @@ static int encode_frame(VC2EncContext *s, AVPacket *avpkt, const AVFrame *frame,
     if (field < 2) {
         ret = ff_get_encode_buffer(s->avctx, avpkt,
                                    max_frame_bytes << s->interlaced, 0);
-        if (ret) {
-            av_log(s->avctx, AV_LOG_ERROR, "Error getting output packet.\n");
+        if (ret < 0)
             return ret;
-        }
         init_put_bits(&s->pb, avpkt->data, avpkt->size);
     }