watchdog: s3c2410: add restart handler

watchdog: s3c2410: add restart handler

On a lot of Samsung systems the watchdog is responsible for restarting the
system and until now this code was contained in plat-samsung/watchdog-reset.c.

With the introduction of the restart handlers, this code can now move into
driver itself, removing the need for arch-specific code.

Tested on a S3C2442 based GTA02

Signed-off-by: Heiko Stuebner <[email protected]>
Signed-off-by: Guenter Roeck <[email protected]>
Signed-off-by: Wim Van Sebroeck <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>