xiaomi-aries: new device (Xiaomi Mi2) (!171)

Finally got display working, but it's based on MoKee kernel which is
also hosted on GitHub by community. So what works:

* USB Networking
* Flashing
* Touchscreen
* Display
* Weston with Xwayland

The device boots and shows the splash screen properly, after about 3
sec the screen went black. I had to
"echo 127 > /sys/devices/i2c-0/0-0038/leds/lm3530-backlight/brightness"
to make the backlight work, even though the value of it was already
127.

[skip ci]: this was built successfully in CI already