[ARM] 4518/1: S3C: Rename watchdog configuration options

Rename the S3C24XX configuration options for the watchdog
boot controls for moving to the arch/arm/plat-s3c moves.

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