xilinx: zynqmp: Do not setup boot_targets if driver is not enabled

xilinx: zynqmp: Do not setup boot_targets if driver is not enabled

SOC can boot in the device which is not accessible from APU and running
this is detected as error which ends up in stopping boot process.
Boot mode detection and logic around is present to setup priority on boot
devices that SOC boot device is likely also used for booting OS.
Change logic to detect this case with showing message about it but don't fail
in boot process and don't prioritize boot device in this case.

Signed-off-by: Venkatesh Yadav Abbarapu <venkatesh.abbarapu@amd.com>
Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/20230904032035.11926-4-venkatesh.abbarapu@amd.com