watchdog: ziirave_wdt: Don't bail out on unexpected timeout value

Reprogramming bootloader on watchdog MCU will result in reported
default timeout value of "0". That in turn will be unnecessarily
rejected by the driver as invalid device (-ENODEV). Simplify probe to
read stored timeout value, set it to a sane default if it is bogus,
and then program that value unconditionally.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Rick Ramstetter <rick@anteaterllc.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190812200906.31344-5-andrew.smirnov@gmail.com


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