watchdog: make DesignWare watchdog allow users to set bigger timeout value

watchdog_dev.c provides means to allow users to set bigger timeout value
than HW can support, make DesignWare watchdog align with this.

Signed-off-by: Peng Wang <peng.1.wang@nokia-sbell.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/8fa54e92c6cd4544a7a3eb60a373ac43@nokia-sbell.com


Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>