ARM: S3C244X: Merge plat-s3c24xx s3c2440.h and s3c2442.h into s3c244x.h

Merge these two headers into one, these two SoCs are so similar.

Note, correct fault in mach-smdk2443.h including the wrong header.

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