watchdog: s3c2410: Fail probe if can't find valid timeout

Driver can't work properly if there no valid timeout was found in
s3c2410wdt_set_heartbeat(). Ideally, that function should be reworked in
a way that it's always able to find some valid timeout. As a temporary
solution let's for now just fail the driver probe in case the valid
timeout can't be found in s3c2410wdt_set_heartbeat() function.

Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Suggested-by: Guenter Roeck <linux@roeck-us.net>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20211107202943.8859-4-semen.protsenko@linaro.org


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