Great, this compiles for the STM32F070. Thanks!
Now I tried to compile for STM32F072, but without luck. The board configuration is based on the nucleo F070 board (F072 not yet in official board folder). Also added above lines to the dts file.
The USB-related entries of both SOCs under dts/arm/st are exactly the same. Is there some other location where the USB support has to be configured for the SOC?
I enabled usb node in stm32f072b_disco board device tree file and the generated output was fine. Try to base your board's configuration files on stm32f072b_disco.