avcodec/alsdec: Fix integer overflow with quant_cof

Fixes: signed integer overflow: -210824 * 16384 cannot be represented in type 'int'
Fixes: 28670/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_ALS_fuzzer-5682310846480384

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 7ce40dde03)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/alsdec.c

@@ -762,7 +762,7 @@ static int read_var_block_data(ALSDecContext *ctx, ALSBlockData *bd)
             }
 
             for (k = 2; k < opt_order; k++)
-                quant_cof[k] = (quant_cof[k] * (1 << 14)) + (add_base << 13);
+                quant_cof[k] = (quant_cof[k] * (1U << 14)) + (add_base << 13);
         }
     }