tools/target_dec_fuzzer: Adjust threshold for EACMV

Fixes: Timeout
Fixes: 382988735/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_EACMV_fuzzer-5278721465974784

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 8f4eb0fe03aca552d375e2bce019a5da785f50d5)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

tools/target_dec_fuzzer.c

@@ -237,6 +237,7 @@ int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
     case AV_CODEC_ID_DVB_SUBTITLE: av_dict_set_int(&opts, "compute_clut", -2, 0); break;
     case AV_CODEC_ID_DXA:         maxpixels  /= 32;    break;
     case AV_CODEC_ID_DXV:         maxpixels  /= 32;    break;
+    case AV_CODEC_ID_CMV:         maxpixels  /= 256;   break;
     case AV_CODEC_ID_EXR:         maxpixels  /= 1024;  break;
     case AV_CODEC_ID_FFV1:        maxpixels  /= 32;    break;
     case AV_CODEC_ID_FFWAVESYNTH: maxsamples /= 16384; break;