ALSA: firewire-motu: add alternative functions to detect packet format for protocol v2

This commit adds alternative functions to detect packet format so that
each function corresponds to each model.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20200519111641.123211-8-o-takashi@sakamocchi.jp


Signed-off-by: Takashi Iwai <tiwai@suse.de>