dt-bindings: watchdog: samsung-wdt: Define cluster constraints top-level

Properties should be always constrained in top-level part of the
bindings, so move the samsung,cluster-index constrain from if: block.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: krzk

Documentation/devicetree/bindings/watchdog/samsung-wdt.yaml

@@ -49,6 +49,7 @@ properties:
 
   samsung,cluster-index:
     $ref: /schemas/types.yaml#/definitions/uint32
+    enum: [0, 1, 2]
     description:
       Index of CPU cluster on which watchdog is running (in case of Exynos850,
       Exynos990 or Google gs101).
@@ -104,8 +105,6 @@ allOf:
           items:
             - const: watchdog
             - const: watchdog_src
-        samsung,cluster-index:
-          enum: [0, 1, 2]
       required:
         - samsung,cluster-index
     else: