ARM: S3C24XX: Move s3c2443-clock.c to mach-s3c24xx

S3C-SoCs starting with the S3C2443 can share a lot of functionality.
The file can collect more common code of these SocS later on and
therefore gets a new name to reflect this future purpose.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>