remove useless assignment

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@11318 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

libavcodec/ptx.c

@@ -30,7 +30,6 @@ static int ptx_init(AVCodecContext *avctx) {
 
     avcodec_get_frame_defaults(&s->picture);
     avctx->coded_frame= &s->picture;
-    s->picture.data[0] = NULL;
 
     return 0;
 }