avfilter/af_crystalizer: use outlink instead of inlink

Doesn't change anything but is more correct.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavfilter/af_crystalizer.c

@@ -203,7 +203,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
     if (av_frame_is_writable(in)) {
         out = in;
     } else {
-        out = ff_get_audio_buffer(inlink, in->nb_samples);
+        out = ff_get_audio_buffer(outlink, in->nb_samples);
         if (!out) {
             av_frame_free(&in);
             return AVERROR(ENOMEM);