dt-bindings: mfd: Add ROHM BD71828 system-power-controller property

As the PMIC can power off the system, add the corresponding property.
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Acked-by: Matti Vaittinen <mazziesaccount@gmail.com>
Link: https://lore.kernel.org/r/20240402111700.494004-2-andreas@kemnade.infoSigned-off-by: Lee Jones <lee@kernel.org>

Documentation/devicetree/bindings/mfd/rohm,bd71828-pmic.yaml

@@ -73,6 +73,8 @@ properties:
       used to mark the pins which should not be configured for GPIO. Please see
       the ../gpio/gpio.txt for more information.
 
+  system-power-controller: true
+
 required:
   - compatible
   - reg