uboot-imx

arm: mach-keystone: Modify secure image size before copy

The size of the secure image does not include the size of the
header, subtract this out before we move the image or we grab
extra data after the image.

Signed-off-by: Andrew F. Davis <afd@ti.com>
Reviewed-by: Lokesh Vutla <lokeshvutla@ti.com>