dt-bindings: arm: sunxi: Add PocketBook 614 Plus

Add a new board name.

Signed-off-by: Denis Burkov <hitechshell@mail.ru>
Acked-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20240415173416.13838-1-hitechshell@mail.ru


Signed-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>