MPEG4Writer: Enforce CSD size check only for MPEG-4 audio/video

CSD size restriction to accomodate in 1-byte is not applicable
to all codecs. Esp. avc and hevc can easily exceed 128 bytes.
Restrict the 128-byte size-check only for MPEG-4 A/V

Bug: 30684941
Change-Id: I777bb357f72065b6ebe854122f9ee2080efd54aa
1 file changed