avcodec/nellymoserdec: Don't use invalid AVPacketSideDataType

Commits 957a593c and
11828b88 made the flv demuxer export
a certain flag as side data to be used by the nellymoser decoder for
mid-stream sample rate changes. It used a custom side data type 'F' that
was never officially documented.

Yet since 2215c39e (merged in commit
52c522c7) this information is exported
via the properly documented AV_PKT_DATA_PARAM_CHANGE side data.
The merge commit therefore stopped exporting the 'F' sidedata; yet the
changes in the Nellymoser decoder (which are now dead code (and would
become dangerous if lots of new side data types were added)) have not
been removed. This commit does this.
Reviewed-by: Anton Khirnov <anton@khirnov.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavcodec/nellymoserdec.c

@@ -143,7 +143,6 @@ static int decode_tag(AVCodecContext *avctx, void *data,
 {
     AVFrame *frame     = data;
     const uint8_t *buf = avpkt->data;
-    const uint8_t *side=av_packet_get_side_data(avpkt, 'F', NULL);
     int buf_size = avpkt->size;
     NellyMoserDecodeContext *s = avctx->priv_data;
     int blocks, i, ret;
@@ -160,15 +159,6 @@ static int decode_tag(AVCodecContext *avctx, void *data,
         av_log(avctx, AV_LOG_WARNING, "Leftover bytes: %d.\n",
                buf_size % NELLY_BLOCK_LEN);
     }
-    /* Normal numbers of blocks for sample rates:
-     *  8000 Hz - 1
-     * 11025 Hz - 2
-     * 16000 Hz - 3
-     * 22050 Hz - 4
-     * 44100 Hz - 8
-     */
-    if(side && blocks>1 && avctx->sample_rate%11025==0 && (1<<((side[0]>>2)&3)) == blocks)
-        avctx->sample_rate= 11025*(blocks/2);
 
     /* get output buffer */
     frame->nb_samples = NELLY_SAMPLES * blocks;