Adds an additional image type needed for supporting secure keystone
devices. The build generates u-boot_HS_MLO which can be used to boot
from all media on secure keystone devices.
Signed-off-by: Madan Srinivas <madans@ti.com>
Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Tom Rini <trini@konsulko.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>