watchdog: meson_gxbb_wdt: add timeout parameter

Add timeout module parameter

Signed-off-by: Artem Lapkin <art@khadas.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20210730041355.2810397-3-art@khadas.com


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