dt-bindings: display: imx: Add deprecated property display and display0

Add deprecated property display and display0 to allow old platform lx1021a
(>10 years) to put display timing under dcu node.

Following patch rename display@0 to display0 and mode0 to timing0. Fix
below CHECK_DTBS warnings:
arch/arm/boot/dts/nxp/ls/ls1021a-iot.dtb: dcu@2ce0000 (fsl,ls1021a-dcu): 'display', 'display@0' do not match any of the regexes: '^pinctrl-[0-9]+$'
        from schema $id: http://devicetree.org/schemas/display/fsl,ls1021a-dcu.yaml

Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Frank Li <Frank.Li@nxp.com>

Documentation/devicetree/bindings/display/fsl,ls1021a-dcu.yaml

@@ -45,6 +45,15 @@ properties:
     $ref: /schemas/types.yaml#/definitions/phandle
     description: The phandle to the timing controller node.
 
+  display:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description: phandle to display panel
+    deprecated: true
+
+  display0:
+    $ref: panel/panel-common.yaml#
+    deprecated: true
+
 required:
   - compatible
   - reg
@@ -53,6 +62,19 @@ required:
 
 additionalProperties: false
 
+allOf:
+  - if:
+      not:
+        properties:
+          compatible:
+            contains:
+              enum:
+                - fsl,ls1021a-dcu
+    then:
+      properties:
+        display: false
+        display0: false
+
 examples:
   - |
     display-controller@2ce0000 {