arm: sunxi: add initial H616 DTSI and headers

arm: sunxi: add initial H616 DTSI and headers

This commit introduces H616 DTSI file and dt-bindings headers needed for
device tree files.

Files are taken from v3 Linux H616 support submission[1], as the
H616 .dtsi file is not merged upstream yet.

[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2021-January/632082.html

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Andre Przywara <andre.przywara@arm.com>