dt-bindings: document rockchip rk3328-evb board

Use "rockchip,rk3328-evb" compatible string for Rockchip RK3328
evaluation board.
Signed-off-by: Liang Chen <cl@rock-chips.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.txt

@@ -134,6 +134,10 @@ Rockchip platforms device tree bindings
     Required root node properties:
      - compatible = "rockchip,rk3288-fennec", "rockchip,rk3288";
 
+- Rockchip RK3328 evb:
+    Required root node properties:
+      - compatible = "rockchip,rk3328-evb", "rockchip,rk3328";
+
 - Rockchip RK3399 evb:
     Required root node properties:
       - compatible = "rockchip,rk3399-evb", "rockchip,rk3399";