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

Add a new board name.

Signed-off-by: Denis Burkov <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jernej Skrabec <[e-mail]>

Documentation/devicetree/bindings/arm/sunxi.yaml

···
           - const: pocketbook,touch-lux-3
           - const: allwinner,sun5i-a13
 
+      - description: PocketBook 614 Plus
+        items:
+          - const: pocketbook,614-plus
+          - const: allwinner,sun5i-a13
+
       - description: Point of View Protab2-IPS9
         items:
           - const: pov,protab2-ips9