ARM: SAMSUNG: Cleanup plat-samsung/devs.c and devs.h

This patch merges each dev files to one devs.c file in
plat-samsung directory and this help to keep it more
easily to reduce plat- directories such as plat-s3c24xx
and plat-s5p.

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