watchdog: at91sam9_wdt: update device tree doc

Add new at91sam9 watchdog properties to the documentation.

Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com>
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
1 file changed