ARM: dts: sunxi: Add Allwinner A80 dtsi

The Allwinner A80 is a new multi-purpose SoC with 4 Cortex-A7 and
4 Cortex-A15 cores in a big.LITTLE architecture, and a 64-core
PowerVR G6230 GPU.

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>