ARM: dts: sun8i: Add board dts file for Banana Pi M2 Berry

The Banana Pi M2 Ultra is an SBC based on the Allwinner V40 SoC (same as
the R40 SoC). The form factor is similar to the Raspberry Pi series.

It features:

- X-Powers AXP221s PMIC connected to i2c0
- 1GiB DDR3 DRAM
- microSD slot
- MicroUSB Type-B port for power and connected to usb0
- HDMI output
- MIPI DSI connector
- 4 USB Type-A ports (connected to the usb1 controller via a hub)
- gigabit ethernet with Realtek RTL8211E transceiver
- WiFi/Bluetooth with AP6212 module, with external antenna connector
- SATA and power connectors for native SATA support
- camera sensor connector
- audio out headphone jack
- red and green LEDs
- debug UART pins
- Raspberry Pi B+ compatible GPIO header
- power and reset buttons

This patch adds a dts file that enables UART, MMC and PMIC support.

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