fpga: zynqmp: support loading authenticated images

Add supporting new compatible string "u-boot,zynqmp-fpga-ddrauth" to
handle loading authenticated images (DDR).

Based on solution by Jorge Ramirez-Ortiz <jorge@foundries.io>

Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
Tested-by: Ricardo Salveti <ricardo@foundries.io>
Link: https://lore.kernel.org/r/20220722141614.297383-13-oleksandr.suvorov@foundries.io


Signed-off-by: Michal Simek <michal.simek@amd.com>