Started through setting U-Boot as kernel manually. I suppose QEMU is not replicating the search for boot.bin on first partition, as the hardware does (needs verification). Built newest U-Boot (2017) from Xilinx to check if there would be less problems, than with one from 2014 from apertus°.

target_dir="./images/mymod"
image="beta_20170109.dd"
dtb="devicetree.dtb"
kernel="u-boot

./qemu/aarch64-softmmu/qemu-system-aarch64 \
-M arm-generic-fdt-7series -m 4GB -machine linux=on \
-serial null -serial mon:stdio -nographic -boot mode=3 \
-dtb $target_dir/$dtb \
-kernel $target_dir/$kernel \
-drive file=$target_dir/$image,if=sd,format=raw,index=0

Still does not run fully automatically, "run sdboot" has to be called, afterwards the system boots. Someone has to check the state of emulation, if important parts of hardware are initialized.