WIP: Add elements to create pinephone-pro image

This is only a start to keep things going; probably a lot of stuff can be shared with the elements in pinebook-pro, but what I've seen so far we still need different set of patches

Useful links:

• https://gitlab.manjaro.org/manjaro-arm/packages/core?utf8=%E2%9C%93&filter=pinephonepro
• https://gitlab.manjaro.org/manjaro-arm/packages/community/pinephone
• https://gitlab.com/mobian1/devices/pinephonepro-support
• https://gitlab.com/mobian1/devices/rockchip-linux
• https://gitlab.com/mobian1/mobian-recipes
• https://gitlab.com/mobian1/devices/eg25-manager
• https://gitlab.com/pine64-org/linux

Towards #338 (closed)