watchdog: Convert to use device property

Use device_property_read_u32() instead of of_property_read_u32() to support
reading the timeout from non-devicetree sources.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250311141009.756975-1-linux@roeck-us.net


Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>