dt-bindings: watchdog: nxp,pnx4008-wdt: allow clocks property

Allow clocks property to fix below CHECK_DTB warning:
  arch/arm/boot/dts/nxp/lpc/lpc3250-phy3250.dtb: watchdog@4003c000 (nxp,pnx4008-wdt): Unevaluated properties are not allowed ('clocks' was unexpected)

Signed-off-by: Frank Li <Frank.Li@nxp.com>
Acked-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20250624201227.2515275-1-Frank.Li@nxp.com
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

Author: nxpfrankli

Documentation/devicetree/bindings/watchdog/nxp,pnx4008-wdt.yaml

@@ -19,6 +19,9 @@ properties:
   reg:
     maxItems: 1
 
+  clocks:
+    maxItems: 1
+
 required:
   - compatible
   - reg