[Letux-kernel] PinePhone support

[H. Nikolaus Schaller]

It was a little broken (in boot.scr) but now

makesd -v latest pinephone-1.0 -v stable -r quantumstep

seems to work again on my Developer Edition device.

I have added pinephone-1.1 and pinephone-1.2 macros
which just install a different bootscr that loads
a different DTB but obviously I can't test that.

I am not sure if the u-boot can do hardware version
detection and can be made load different device trees
like we do on Pyra. Then we could simplify this again.

Charging and USB detection seems to be broken with
letux-5.10.0 but USB gadget works. Was the opposite
with some -rc I had installed before (unfortunately
I didn't write down which one).

BR,
Nikolaus