avcodec/libutvideodec: free coded_frame with av_frame_free() instead if av_free*

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

libavcodec/libutvideodec.cpp

@@ -174,7 +174,7 @@ static av_cold int utvideo_decode_close(AVCodecContext *avctx)
     UtVideoContext *utv = (UtVideoContext *)avctx->priv_data;
 
     /* Free output */
-    av_freep(&avctx->coded_frame);
+    av_frame_free(&avctx->coded_frame);
     av_freep(&utv->buffer);
 
     /* Finish decoding and clean up the instance */