avcodec/libopenjpegenc: Replace av_frame_alloc() and av_frame_ref() by av_frame_clone()

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

libavcodec/libopenjpegenc.c

@@ -501,13 +501,9 @@ static int libopenjpeg_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     case AV_PIX_FMT_GBRP12:
     case AV_PIX_FMT_GBRP14:
     case AV_PIX_FMT_GBRP16:
-        gbrframe = av_frame_alloc();
+        gbrframe = av_frame_clone(frame);
         if (!gbrframe)
             return AVERROR(ENOMEM);
-        if ((ret = av_frame_ref(gbrframe, frame)) < 0) {
-            av_frame_free(&gbrframe);
-            return ret;
-        }
         gbrframe->data[0] = frame->data[2]; // swap to be rgb
         gbrframe->data[1] = frame->data[0];
         gbrframe->data[2] = frame->data[1];