ALSA: ctxfi: Fix missing SPDIFI1 index handling

In the Linux kernel, the following vulnerability has been resolved: 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.