Remove packet returning in ff_rm_parse_packet() if we're using the packet

cache, since this can already be accessed through ff_rm_retrieve_cache().
See "[PATCH] rmdec.c: remove cache access duplication" thread.

Originally committed as revision 18009 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/rm.h

@@ -64,9 +64,9 @@ int ff_rm_read_mdpr_codecdata (AVFormatContext *s, ByteIOContext *pb,
  * @param flags pointer to an integer containing the packet flags, may be
                 updated
  * @param ts pointer to timestamp, may be updated
- * @return >=0 on success (where >0 indicates there are cached samples that
- *         can be retrieved with subsequent calls to ff_rm_retrieve_cache()),
- *         errno codes on error
+ * @return <0 on error, 0 if a packet was placed in the \p pkt pointer. A
+ *         value >0 means that no data was placed in \p pkt, but that cached
+ *         data is available by calling ff_rm_retrieve_cache().
  */
 int ff_rm_parse_packet (AVFormatContext *s, ByteIOContext *pb,
                         AVStream *st, RMStream *rst, int len,