ARM: S3C24XX: Move common-smdk code to mach directory

This code is used by boards based on the S3C2410/S3C2440/S3C2416.
The patch includes also a rename of the option, as the smdk code
is not a mach itself, but only an extension with common code.

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