Add audio support #9
Description
Port over all the audio patches including synchronisation features:
CreatorDev/openwrt#237 and CreatorDev/openwrt#242 were closed down after cleanup but the work was just pushed to a temporary branch for now TODO-put-link-to-branch-here in order to simplify upstreaming.
Main considerations are:
- start_at implementation including abort functions
- atu driver
- event timer driver
- pistachio sound card (based on upstream dts because it's different to internal repos)
- lede kmod for pistachio-sound-soc
Acceptance criteria:
- alsa-utils speaker test needs to build and be working