csky: C-SKY SMP supported.

This is the first verion for C-SKY SMP. It only support ck860mp and up
to 4 cores.

ck860mp introduce some new features for atomic operation, eg:
 - ldex/stex
 - tlbi
 - mem barreior
 - soc multi-cores reset controller

It's new start point for C-SKY high performance SMP CPU.

Signed-off-by: Guo Ren <ren_guo@c-sky.com>