dt-bindings: display: meson-vpu: Add missing amlogic,canvas property

This property was already mentioned in the old textual bindings
amlogic,meson-vpu.txt, but got dropped during conversion.
Adding it back similar to amlogic,gx-vdec.yaml.

Fixes: 6b9ebf1e ("dt-bindings: display: amlogic, meson-vpu: convert to yaml")
Signed-off-by: Alexander Stein <alexander.stein@mailbox.org>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20211219094155.177206-1-alexander.stein@mailbox.org

Documentation/devicetree/bindings/display/amlogic,meson-vpu.yaml

@@ -78,6 +78,10 @@ properties:
   interrupts:
     maxItems: 1
 
+  amlogic,canvas:
+    description: should point to a canvas provider node
+    $ref: /schemas/types.yaml#/definitions/phandle
+
   power-domains:
     maxItems: 1
     description: phandle to the associated power domain
@@ -106,6 +110,7 @@ required:
   - port@1
   - "#address-cells"
   - "#size-cells"
+  - amlogic,canvas
 
 additionalProperties: false
 
@@ -118,6 +123,7 @@ examples:
         interrupts = <3>;
         #address-cells = <1>;
         #size-cells = <0>;
+        amlogic,canvas = <&canvas>;
 
         /* CVBS VDAC output port */
         port@0 {