dt-bindings: power: supply: richtek,rt5033: Add missing power-supply ref

Reference the common power supply schema to bring the definition of
monitored-battery property.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20250604-dt-bindings-psy-monitored-battery-v1-4-7f755ff75218@linaro.org
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

Author: krzk

Documentation/devicetree/bindings/power/supply/richtek,rt5033-charger.yaml

@@ -18,7 +18,6 @@ properties:
     const: richtek,rt5033-charger
 
   monitored-battery:
-    $ref: /schemas/types.yaml#/definitions/phandle
     description: |
       Phandle to the monitored battery according to battery.yaml. The battery
       node needs to contain five parameters.
@@ -54,6 +53,9 @@ properties:
 required:
   - monitored-battery
 
+allOf:
+  - $ref: power-supply.yaml#
+
 additionalProperties: false
 
 examples: