avformat/dsfdec: Change order of operations in bitrate computation

Fixes: signed integer overflow: 538976288 * 67372036 cannot be represented in type 'int'
Fixes: 29102/clusterfuzz-testcase-minimized-ffmpeg_dem_DSF_fuzzer-6751696819716096

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/dsfdec.c

@@ -130,7 +130,7 @@ static int dsf_read_header(AVFormatContext *s)
         return AVERROR_INVALIDDATA;
     }
     st->codecpar->block_align *= st->codecpar->channels;
-    st->codecpar->bit_rate = st->codecpar->channels * st->codecpar->sample_rate * 8LL;
+    st->codecpar->bit_rate = st->codecpar->channels * 8LL * st->codecpar->sample_rate;
     avpriv_set_pts_info(st, 64, 1, st->codecpar->sample_rate);
     avio_skip(pb, 4);