dt-bindings: arm: amlogic: add Odroid-N2 binding

Add compatible for the Amlogic G12B (S922X) SoC based Odroid-N2 SBC
from HardKernel.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>