ALSA: firewire-motu: parse messages for output parameters in register DSP model

This commit parses message and cache current parameters of output
function, commonly available for all of register DSP model.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20211015080826.34847-7-o-takashi@sakamocchi.jp
Signed-off-by: Takashi Iwai <tiwai@suse.de>