ARM: S3C24XX: Merge s3c2442 and s3c2440 machines into mach-s3c2440

Move the pair of machines in arch/arm/mach-s3c2442 into the mach-s3c2440
directory as the S3C2440 and S3C2442 are very close.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>