ALSA: oxfw: add explicit device entry for Loud Technologies Tapco Link.FireWire 4x6

Loud Technologies Tapco Link.FireWire 4x6 is identified as the model
with OXFW970 ASIC.

This commit adds explicit entry for the model.

Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Link: https://lore.kernel.org/r/20210518084557.102681-6-o-takashi@sakamocchi.jp


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