dt-bindings: arm: amlogic: add support for the ODROID-N2+

HardKernel ODROID-N2+ uses a revised Amlogic S922X v2 chip that supports
higher cpu clock speeds than the original ODROID-N2.

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: Rob Herring <robh@kernel.org>
Acked-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/r/20200915152432.30616-3-narmstrong@baylibre.com