Initial support for the Pine64 Pinephone

[Peter Robinson]

Hi,

This is an initial patch set to support the PinePhone. The patches were tested
on the Braveheart Edition (1.1) of the phone with a serial console cable attached.
There's not currently U-Boot output on the screen, for starters the device tree
support for the panel hasn't landed upstream yet so I'll send that in a follow
up patch series, similarly I'll send a patch set to add support for the Consumer
Edition (1.2) once it lands upstream. For me this allows the phone to boot off
either eMMC or mSD card, USB-C for USB-2/display doesn't currently work as I 
think there will need to be support for the ANX7688 USB-C bridge.

Peter