firewire-lib: add helper function to set the size of data block directly

Signed-off-by: sakamocchi <o-takashi@sakamocchi.jp>
firewire-lib: add payload_cb callback function to handle the contents of payload

Signed-off-by: sakamocchi <o-takashi@sakamocchi.jp>
firewire-lib: remove unused members and functions

Signed-off-by: sakamocchi <o-takashi@sakamocchi.jp>
firewire-speakers: apply new way

Signed-off-by: sakamocchi <o-takashi@sakamocchi.jp>