dt-bindings: arm: add Rockchip rk3036-evb board

A test with the command below gives this error:

arch/arm/boot/dts/rk3036-evb.dt.yaml: /: compatible:
['rockchip,rk3036-evb', 'rockchip,rk3036']
is not valid under any of the given schemas

This board was somehow never added to the documentation.
Fix this error by adding the rk3036-evb board to rockchip.yaml.

make ARCH=arm dtbs_check
DT_SCHEMA_FILES=Documentation/devicetree/bindings/arm/rockchip.yaml
Signed-off-by: Johan Jonker <jbx6244@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20200302092759.3291-2-jbx6244@gmail.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

Documentation/devicetree/bindings/arm/rockchip.yaml

@@ -468,6 +468,11 @@ properties:
           - const: rockchip,r88
           - const: rockchip,rk3368
 
+      - description: Rockchip RK3036 Evaluation board
+        items:
+          - const: rockchip,rk3036-evb
+          - const: rockchip,rk3036
+
       - description: Rockchip RK3228 Evaluation board
         items:
           - const: rockchip,rk3228-evb