conf: USB-Audio: Add ASUS ROG Zenith II S/PDIF device mapping

[GitHub pull_request - opened <github@alsa-project.org>]

alsa-project/alsa-lib pull request #533 was opened from byrcolin:

Fixes #532

Adds the two onboard USB audio codecs of the ASUS ROG Zenith II Extreme (TRX40) to the `USB-Audio.pcm.iec958_device` table:

- `"Zenith II Main Audio" 1` (`0b05:1916`, Realtek ALC1220-VB): S/PDIF is PCM device 1; device 0 is the 8-channel analog output. Without this, `iec958:` opened device 0 and the IEC958 output in PipeWire/PulseAudio played to the analog jacks.
- `"Zenith II Front Headphone" 999` (`0b05:1915`): analog-only codec with no digital output, so `iec958:` should not open it.

Tested on AlmaLinux 10.2 (alsa-lib 1.2.15.3, PipeWire 1.4.11): `iec958:CARD=Audio` opens `hw:0,1`, audio plays over optical S/PDIF, and the front headphone codec shows up as analog stereo only.

This change was created by Claude (Anthropic's Claude Opus 5.5, high effort) via Claude Code and tested as working on the affected hardware by Colin Byrne.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Request URL   : https://github.com/alsa-project/alsa-lib/pull/533
Patch URL     : https://github.com/alsa-project/alsa-lib/pull/533.patch
Repository URL: https://github.com/alsa-project/alsa-lib