U-Boot job builds gateware again.

For some reason, the U-Boot job builds again the gateware. https://gitlab.cern.ch/be-cem-edl/diot/zynqmp/boot-image/-/jobs/42903891

Maybe it has to do something with which artifacts are being fetched? Because from the way the make command is currently executed, we enter both device-tree and gateware directories and execute make. So maybe gateware should be a prerequisite ( needs: ["gateware"]) for uboot as well?