arch/csky: add support for the ck860 core
ck860 is newest CPU core of C-SKY with high performance & SMP
supported.
Signed-off-by: Guo Ren <ren_guo@c-sky.com>
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>