apple-iphone7: new device (Apple iPhone 7/7+)

This is the continuation of my work for a PostmarketOS port based on my blog post here and @MartijnBraam kernel and devices packages here.

The downstream kernel was provided by Corellium. PogoOS by the Checkra1n team is used to boot the Linux kernel.

This merge request provides a just a kernel which is able to boot. Further instructions on how to use it will be provided on the PostmarketOS wiki later on.

This is my first merge request so I hope it is not too bad ;)

Best regards Jonas