To avoid hardcoded offset when adding u-boot.cnt to flash.bin, we use
flexible offset which is calculated based on the size of the container
image generated int the first stage. And pad u-boot.cnt at 1KB
alignment.
So add code to get the offset when SPL loading u-boot.cnt.
Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>