arm64: dts: meson: convert ODROID-N2 to dtsi

Convert the current ODROID-N2 dts into a common dtsi in preparation
for adding ODROID-N2+ support.

Signed-off-by: Christian Hewitt <christianshewitt@gmail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Kevin Hilman <khilman@baylibre.com>
Acked-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20200915152432.30616-2-narmstrong@baylibre.com