ALSA: ctxfi: Fix missing SPDIFI1 index handling

ALSA: ctxfi: Fix missing SPDIFI1 index handling

SPDIF1 DAIO type isn't properly handled in daio_device_index() for
hw20k2, and it returned -EINVAL, which ended up with the out-of-bounds
array access.  Follow the hw20k1 pattern and return the proper index
for this type, too.

Reported-and-tested-by: Karsten Hohmeier <linux@hohmatik.de>
Closes: https://lore.kernel.org/20260315155004.15633-1-linux@hohmatik.de
Cc: <stable@vger.kernel.org>
Link: https://patch.msgid.link/20260329091240.420194-1-tiwai@suse.de
Signed-off-by: Takashi Iwai <tiwai@suse.de>