ARMv8: Add secure sections for PSCI text and data

ARMv8: Add secure sections for PSCI text and data

This patch adds secure_text, secure_data and secure_stack sections for ARMv8 to
hold PSCI text and data, and it is based on the legacy implementation of ARMv7.

ARMV8_SECURE_BASE defines the address for PSCI secure sections, ARMV8_PSCI and
ARMV8_PSCI_NR_CPUS are firstly used in this patch, so they are introduce here
in Kconfig too.

Signed-off-by: Hongbo Zhang <hongbo.zhang@nxp.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: York Sun <york.sun@nxp.com>