ARM: S3C64XX: To merge devs.c files to one devs.c

This patch moves regarding s3c64xx dev files to one devs.c
file in plat-samsung directory and this help to keep it more
easily.

Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>