uboot-imx

ls1043ardb: PPA: add PPA validation in case of secure boot

As part of Secure Boot Chain of trust, PPA image must be validated
before the image is started.
The code for the same has been added.

Signed-off-by: Aneesh Bansal <aneesh.bansal@nxp.com>
Signed-off-by: Sumit Garg <sumit.garg@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>