watchdog: Add STM32 IWDG driver
This patch adds IWDG (Independent WatchDoG) support for STM32 platform. Signed-off-by: Yannick FERTRE <yannick.fertre@st.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>