ARM: dts: sunxi: Add Allwinner H3 DTSI

The Allwinner H3 is a home entertainment system oriented SoC with
four Cortex-A7 cores and a Mali-400MP2 GPU.
Signed-off-by: Jens Kuske <jenskuske@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>