watchdog: docs: omap_wdt also understands nowayout

The omap_wdt kernel driver also understands the nowayout module
parameter. This updates the watchdog-parameters.txt to reflect this fact.

Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>