dt-bindings: mfd: rk806: Allow system-power-controller property

Declare support for this property.

Signed-off-by: Ondrej Jirman <megi@xff.cz>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://lore.kernel.org/r/20231019165732.3818789-3-megi@xff.cz
Signed-off-by: Lee Jones <lee@kernel.org>

Author: Ondrej Jirman

Documentation/devicetree/bindings/mfd/rockchip,rk806.yaml

@@ -29,6 +29,8 @@ properties:
   '#gpio-cells':
     const: 2
 
+  system-power-controller: true
+
   vcc1-supply:
     description:
       The input supply for dcdc-reg1.