Mainline kernel support

[adminy]

Some if not most of xunlong and collabora's changes landed in mainline. Meaning there should be orange pi 5 plus support.

It would be better than building a branched kernel, and would take less time too since the kernel is built by nixpkgs.

refs:
https://www.reddit.com/r/OrangePI/s/0Y3IgfSbNj

[dvdjv]

According to Collabora mainline status isn't quite there yet to be the default option. However, if you wish to take the advantage of nixpkgs binary cache, you can specify kernelPackages = nixpkgs.linuxPackages_6_<x> in your config section.