MIPS: CPS: Introduce struct cluster_boot_config

In preparation for supporting multi-cluster systems, introduce a struct
cluster_boot_config as an extra layer in the boot configuration
maintained by the MIPS Coherent Processing System (CPS) SMP
implementation. For now only one struct cluster_boot_config will be
allocated & we'll simply defererence its core_config field to find the
struct core_boot_config array which can be used to boot as usual.

Signed-off-by: Paul Burton <paulburton@kernel.org>
Signed-off-by: Dragan Mladjenovic <dragan.mladjenovic@syrmia.com>
Signed-off-by: Aleksandar Rikalo <arikalo@gmail.com>
Tested-by: Serge Semin <fancer.lancer@gmail.com>
Tested-by: Gregory CLEMENT <gregory.clement@bootlin.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>