ARM: S3C24XX: Removed unneeded dependency on CPU_S3C2412

S3C2412 boards are already under "if CPU_S3C2412" condition, so
additional dependencies on this symbol can be removed.

Signed-off-by: Alexander Shiyan <shc_work@mail.ru>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>