avformat/avformat: Remove redundant "NOT PART OF PUBLIC API"

AVStream.request_probe as well as AVStream.mux_ts_offset are below the
separator of public and private fields, so that a further "NOT PART OF
PUBLIC API" is redundant.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/avformat.h

@@ -1120,7 +1120,6 @@ typedef struct AVStream {
      * -1   -> probing finished
      *  0   -> no probing requested
      * rest -> perform probing with request_probe being the minimum score to accept.
-     * NOT PART OF PUBLIC API
      */
     int request_probe;
     /**
@@ -1166,7 +1165,6 @@ typedef struct AVStream {
 
     /**
      * Timestamp offset added to timestamps before muxing
-     * NOT PART OF PUBLIC API
      */
     int64_t mux_ts_offset;