armv8: ls1012a: Add support of PPA

The PPA implements PSCI which requires for power managment.

Added support of PPA for LS1012AQDS, LS1012ARDB and LS1012AFRDM.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Abhimanyu Saini <abhimanyu.saini@nxp.com>
Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>