Just for information.
I created new platform build scripts based on work by pkendall64 (https://github.com/pkendall64/platform-orangepi). This script allows you to create platform files based on armbian build system and includes improvements i2s driver from codekipper (https://github.com/codekipper/linux-sunxi/blob/upstream-i2s/sound/soc/sunxi/sun4i-i2s.c) and overlays for i2s master and slave. You can find it on github: https://github.com/nikkov/platform-armbian.
Also I corrected armbianimage.sh/armbianconfig.sh in Volumio-Build for compile Volumio image with this platform files (https://github.com/nikkov/Volumio-Build).
Image for nanopi neo, air and neo2 for testing: https://drive.google.com/drive/folders/0B4dQ_SnxXHi4a2REN2ZGZzlQczA?usp=sharing
Attention! By default image use i2s in slave mode and without external clock source will not work! You can change i2s mode to master by edit armbianEnv.txt, just replace