Add DisplayPort sound support for Fairphone 5

Merge series from Luca Weiss <luca.weiss@fairphone.com>:

Add the necessary sound card bits and some dts additions to enable sound
over DisplayPort-over-USB-C, e.g. to a connected TV or monitor.

The UCM files can be found here:
https://gitlab.postmarketos.org/postmarketOS/pmaports/-/tree/master/device/testing/device-fairphone-fp5/ucm

This series - in spirit - depends on the series enabling DisplayPort in
the first place, but can land pretty independently, especially the ASoC
bits:
https://lore.kernel.org/linux-arm-msm/20250312-fp5-pmic-glink-dp-v2-0-a55927749d77@fairphone.com/