[pull requests] No SPDIF for Plantronics 3220, Dell AE515

Hello,

The Plantronics Blackwire 3220 Series headset and the Dell Professional Sound Bar AE515 are both USB-audio devices that show up with a digital S/PDIF output that physically doesn't exist.

This can be fixed by adding them to the USB-Audio.pcm.iec958_device list in USB-Audio.conf, with the following names:

"DELL PROFESSIONAL SOUND BAR AE5" "Plantronics Blackwire 3220 Seri"

Patches for the respective devices are in the following alsa-lib pull requests:

https://github.com/alsa-project/alsa-lib/pull/124 https://github.com/alsa-project/alsa-lib/pull/126

Many thanks, James.