ARM: exynos: add support secondary core bootup in big.LITTLE processor.

ARM: exynos: add support secondary core bootup in big.LITTLE processor.

This patch adds support secondary core bootup in big.LITTLE processor
for platsmp. Just core id cannot be used for identification, because
there is a pair of the cores which have same core id. Cluster id have
to be included for their identification. This patch makes cpu index
using cluster id and core id for the calculation of their register
address and the identification. But there is a problem to use cluster id
for core index creation. That is, cluster id does not start from 0 in
old processors which do not have more than one cluster. For example,
Exynos4412's cluster id for its 4 core is 0xa. So I makes all cluster id
to 0 when they are bigger than 1. Normally big.LITTLE processor does not
use platsmp. But at this moment, just for the minimal functionality of
big.LITTLE, this patch adds support for it. This patch can be reverted
after another CPU management method is adopted.

Change-Id: Ifa2d62545dd4174998f962c9608fd6d9b6034c16
Signed-off-by: Hyungwon Hwang <human.hwang@samsung.com>