avformat/chromaprint: Fix writing raw fingerprint

avformat/chromaprint: Fix writing raw fingerprint

The pointer fp after the call to chromaprint_get_raw_fingerpoint() points to an array
of uint32_t whereas the current code assumed just a char stream. Thus when writing the
raw fingerprint, the output would be truncated by a factor of 4.

For reference the declaration of the function from chromaprint.h is:
int chromaprint_get_raw_fingerprint(ChromaprintContext *ctx, uint32_t **fingerprint, int *size);