As shown in the following figure, if you enable the config “u-boot dtb” you can build separate U-Boot dtb with the provided design and you can find the binary in <plnx-proj-root>/images/linux with the name u-boot.dtb. You can change the name with the “uboot dtb package name” option. If you have a dts file to build a separate U-Boot dtb, then you can use the “uboot dts file path” to provide the dts/dtsi files with space separation.
Figure 1. Separate U-Boot DTB