AVUtils: hevc: Return 0 when codec data is malformed

This was returning ERROR_MALFORMED, which is a negative value,
since the function prototype returns size_t, it would be converted
to somewhere near 2**32 and would never fall into the actual error
checking clause in AVUtils::HEVCMuxer::makeHEVCCodecSpecificData.

Fixes android.mediastress.cts.HEVCR1080pAacLongPlayerTest#testPlay00

Ticket: CYNGNOS-1683
Change-Id: I13e6a76cb0ee4a6b730e1eb1023320b74a0539c7