[ARM] 3005/1: S3C2440 - add definition for s3c2440_set_dsc() call in hardware.h

Patch from Ben Dooks

include/asm-arm/arch-s3c2410/hardware.h was missing
the definition for s3c2440_set_dsc()

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