dt-bindings: PCI: dwc: Add rk3588 compatible

PCIe for RK3588 is the same as RK3568.
Signed-off-by: Lucas Tanure <lucas.tanure@collabora.com>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230314135555.44162-2-lucas.tanure@collabora.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

Documentation/devicetree/bindings/pci/rockchip-dw-pcie.yaml

@@ -21,8 +21,12 @@ allOf:
 
 properties:
   compatible:
-    items:
+    oneOf:
       - const: rockchip,rk3568-pcie
+      - items:
+          - enum:
+              - rockchip,rk3588-pcie
+          - const: rockchip,rk3568-pcie
 
   reg:
     items: