[ARM] 4721/1: S3C24XX: Ensure watchdog clock is enbaled for hard reset

If the hard reset routine is using the watchdog, then
ensure that the clock for the watchdog has been enabled
before we try and issue a reset.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>