ARM: dts: sun9i: Add A80 Optimus Board support

The A80 Optimus Board is was launched with the Allwinner A80 SoC.
It was jointly developed by Allwinner and Merrii.

This board has a UART port, a JTAG connector, USB host ports, a USB
3.0 OTG connector, an HDMI output, a micro SD slot, 8G NAND flash,
4G DRAM, a camera sensor interface, a WiFi/BT combo chip, a headphone
jack, IR receiver, and additional GPIO headers.

This patch adds only basic support.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Tested-by: Andreas Färber <afaerber@suse.de>