dt-bindings: panel: raydium,rm67191: Add missing type to 'video-mode'

'video-mode' is missing a type definition and is not a common property. The
type is 'uint32'.
Signed-off-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20220719215201.1877997-1-robh@kernel.org

Documentation/devicetree/bindings/display/panel/raydium,rm67191.yaml

@@ -38,6 +38,7 @@ properties:
       0 - burst-mode
       1 - non-burst with sync event
       2 - non-burst with sync pulse
+    $ref: /schemas/types.yaml#/definitions/uint32
     enum: [0, 1, 2]
 
 required: