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>