Yep, I solved it by right combination of STM32CubMx, SDK and Programmer!STM32CubeMX_v6.2.1, STM32CubeProgrammer_v.2.7.0, Developer Package v3.0.0 и Yocto SDK_v3.0.0 и Starter Package_v3.0.0.Other combinations may create problems. Good luck!

I met this problem too. Then I tried to export the environment variable $FIP_DEPLOYDIR_ROOT.Try to find where is "u-boot-stm32mp157a-dk1-trusted.dtb" file by searching.Go to the building directory. In your case is "...eloper-Package/stm32mp1-openstli...