ARMv8/ls1043ardb: Integrate FSL PPA

The PPA use PSCI to make secondary cores bootup. So when PPA was
enabled, add the CONFIG_ARMV8_PSCI to identify the SMP boot-method
between PSCI and spin-table.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>