Because FIT could not be used for AHAB secure boot on i.MX8,
so switch to use container image that could let SPL verify
ATF and U-Boot with AHAB.
Enable HUSH_PARSER in defconfig to make run netboot could work.
Note: The AHAB related code has not been added.
Signed-off-by: Peng Fan <peng.fan@nxp.com>
