ARM: EXYNOS: Add secure firmware support to secondary CPU bring-up

Boards using secure firmware must use different CPU boot registers and
call secure firmware to boot the CPU.

Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Tomasz Figa <t.figa@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>