SECURE BOOT: support for validation of dynamic image

Some images to be validated are relocated to a dynamic
address at run time. So, these addresses cannot be known
befor hand while signing the images and creating the header
offline.
So, support is required to pass the image address to the
validate function as an argument.
If an address is provided to the function, the address
field in Header is not read and is treated as a reserved
field.

Signed-off-by: Saksham Jain <saksham@freescale.com>
Signed-off-by: Aneesh Bansal <aneesh.bansal@freescale.com>
Acked-by: Ruchika Gupta <ruchika.gupta@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>