This patch adds plat-samsung/cpu.c for detecting of cpu id and
silicon revision.

This patch was originally from Changhwan Youn <chaos.youn@samsung.com>
Acked-by: NChanghwan Youn <chaos.youn@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: NKukjin Kim <kgene.kim@samsung.com>