dt-bindings: arm: rockchip: add Zkmagic A95X Z2 description

Add Zkmagic A95X Z2 description for a board with rk3318 processor.

Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200808160618.15445-3-jbx6244@gmail.com


Signed-off-by: Heiko Stuebner <heiko@sntech.de>