media: dt-bindings: media: imx7-csi: Document i.MX8M power-domains property

The power-domains property is mandatory on i.MX8M Quad and Mini.
Document the property and mark it as required on the aforementioned
variants of the IP, present in those SoCs.
Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>

Documentation/devicetree/bindings/media/nxp,imx7-csi.yaml

@@ -37,6 +37,9 @@ properties:
     items:
       - const: mclk
 
+  power-domains:
+    maxItems: 1
+
   port:
     $ref: /schemas/graph.yaml#/properties/port
 
@@ -50,6 +53,18 @@ required:
 
 additionalProperties: false
 
+allOf:
+  - if:
+      properties:
+        compatible:
+          contains:
+            enum:
+              - fsl,imx8mq-csi
+              - fsl,imx8mm-csi
+    then:
+      required:
+        - power-domains
+
 examples:
   - |
     #include <dt-bindings/clock/imx7d-clock.h>