USB-Audio: Add support for Focusrite 4th Gen devices

alsa-project/alsa-ucm-conf pull request #438 was opened from ChrisLane:

Extending the existing support for Focusrite Scarlett Solo and 2i2 interfaces with support for the 4th Gen devices.

I have a Focusrite Scarlett 2i2 which is what I have tested with and used to get the device ID. For the Solo device, I grabbed the device ID from [linux-hardware.org](https://linux-hardware.org/?id=usb:1235-8218).

Request URL : https://github.com/alsa-project/alsa-ucm-conf/pull/438 Patch URL : https://github.com/alsa-project/alsa-ucm-conf/pull/438.patch Repository URL: https://github.com/alsa-project/alsa-ucm-conf