dt-bindings: gpio: cdns: add Axiado AX3000 GPIO variant

Add binding for Axiado AX3000 GPIO controller. So far, no changes
are known, so it can fallback to default compatible.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Harshit Shah <hshah@axiado.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Author: hshahaxiado

Documentation/devicetree/bindings/gpio/cdns,gpio.yaml

@@ -11,7 +11,12 @@ maintainers:
 
 properties:
   compatible:
-    const: cdns,gpio-r1p02
+    oneOf:
+      - const: cdns,gpio-r1p02
+      - items:
+          - enum:
+              - axiado,ax3000-gpio
+          - const: cdns,gpio-r1p02
 
   reg:
     maxItems: 1