sunxi: Add defconfig and dts for Orange Pi 2 SBC

The Orange Pi 2 is a SBC based on the Allwinner H3 SoC with a uSD slot,
4 USB ports connected via a USB-2 hub, a 10/100M ethernet port using the
SoC's integrated PHY, Wifi via a RTL8189ETV sdio wifi chip, USB OTG, HDMI,
a TRRS headphone jack for stereo out and composite out, a microphone,
an IR receiver, a CSI connector, 2 LEDs, a 3 pin UART header
and a 40-pin GPIO header.

The added dts file is identical to the one submitted to the upstream
kernel.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>