Remove two more non-existing stray Doxygen function arguments.

Originally committed as revision 23977 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/rl2.c

@@ -174,8 +174,6 @@ static av_cold int rl2_decode_init(AVCodecContext *avctx)
  * @param avctx decoder context
  * @param data decoded frame
  * @param data_size size of the decoded frame
- * @param buf input buffer
- * @param buf_size input buffer size
  * @return 0 success, -1 on error
  */
 static int rl2_decode_frame(AVCodecContext *avctx,