ARMv7: PSCI: ls102xa: check target CPU ID before further operations

The input parameter CPU ID needs to be validated before furher oprations such
as CPU_ON, this patch introduces the function to do this.

Signed-off-by: Wang Dongsheng <dongsheng.wang@nxp.com>
Signed-off-by: Hongbo Zhang <hongbo.zhang@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>