avcodec/atrac3plusdec: consume only as many bytes as available

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 6b6ae7c3ea)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/atrac3plusdec.c

@@ -381,7 +381,7 @@ static int atrac3p_decode_frame(AVCodecContext *avctx, void *data,
 
     *got_frame_ptr = 1;
 
-    return avctx->block_align;
+    return FFMIN(avctx->block_align, avpkt->size);
 }
 
 AVCodec ff_atrac3p_decoder = {