During probe try to set the timeout from device tree and fall back to
either the pre-configured timeout set by e.g. the bootloader in case the
watchdog is already running or the default value.

If the watchdog is already running make sure to update the timeout and
tell the framework about the running state to make sure the watchdog is
handled correctly until user space takes over. Updating the timeout also
removes the need for an additional manual ping so we can remove that as
well.
Signed-off-by: Stefan Riedmueller <s.riedmueller@phytec.de>
Reviewed-by: Adam Thomson <Adam.Thomson.Opensource@diasemi.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200403130728.39260-1-s.riedmueller@phytec.deSigned-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>