To share code with some of the newer parts such as the S3C2416, move
parts of arch/arm/mach-s3c2443/clock.c to a common file called
arch/arm/plat-s3c24xx/s3c2443-clock.c.

Update the build configuration to deal with this new file.
Signed-off-by: NBen Dooks <ben-linux@fluff.org>