ARM: dts: sun5i: Add PocketBook Touch Lux 3 support

What works:

- Serial console
- mmc0, mmc2 (both microSD card slots on the board)
- All buttons (gpio and lradc based)
- Power LED
- PMIC
- RTC
- USB OTG/gadgets mode
- Realtek USB WiFi
- Display backlight
- eInk display SPI NOR flash memory

Signed-off-by: Ondrej Jirman <megous@megous.com>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>