aws_transcriber: fix CRC check
This was broken when porting to crc 2, based on:
https://github.com/mrhooray/crc-rs/issues/62#issuecomment-850591181
CRC_32_BZIP2 is a different algorithm from CRC_32_IEEE, try CRC_32_ISO_HDLC instead.
The correct algorithm for replacing checksum_ieee is not CRC_32_BZIP2.