Add the secure boot relevant environment variables to ARM2 and MEK.
When CONFIG_AHAB_BOOT is enabled, we will switch to boot in this
new way:
1. Load the OS container to address 0x88000000
2. Using auth_cntr to authenticate the OS container. It will load the
   kernel and FDT to destination address.
3. Using booti to boot kernel.

Signed-off-by: Ye Li <ye.li@nxp.com>
Acked-by: Peng Fan <peng.fan@nxp.com>