ARM: dts: sun8i: h2+: add support for Banana Pi M2 Zero board

Banana Pi M2 Zero board is a H2+-based board by Sinovoip, with a form
factor and GPIO holes similar to Raspberry Pi Zero.

It features:
- Allwinner H2+ SoC
- Single-chip (16-bit) 512MiB DDR3 DRAM
- Ampak AP6212 Wi-Fi/Bluetooth module
- MicroSD slot
- Two MicroUSB Type-B ports (one can only be used to power the board and
  the other features OTG functionality)
- Two keys, a reset and a GPIO-connected key.
- HDMI Type-C (miniHDMI) connector connected to the HDMI part of H2+.
- CSI connector to connect the camera sensor provided by Sinovoip.

Signed-off-by: Icenowy Zheng <icenowy@aosc.io>
Signed-off-by: Maxime Ripard <maxime.ripard@bootlin.com>