avcodec/mlpdsp: Fix runtime error: signed integer overflow: -24419392 * 128 cannot be represented in type 'int'

Fixes: 1711/clusterfuzz-testcase-minimized-5248503515185152

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 1d04fc94e1)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/mlpdsp.c

@@ -114,7 +114,7 @@ int32_t ff_mlp_pack_output(int32_t lossless_check_data,
         for (out_ch = 0; out_ch <= max_matrix_channel; out_ch++) {
             int mat_ch = ch_assign[out_ch];
             int32_t sample = sample_buffer[i][mat_ch] *
-                          (1 << output_shift[mat_ch]);
+                          (1U << output_shift[mat_ch]);
             lossless_check_data ^= (sample & 0xffffff) << mat_ch;
             if (is32)
                 *data_32++ = sample << 8;