`usbdev_stm32.h` will pull in `usb.h` which causes an error if `USB_H_USER_IS_RIOT_INTERNAL` is not set. Turns out this include is not needed, so just drop it.
`usbdev_stm32.h` will pull in `usb.h` which causes an error if `USB_H_USER_IS_RIOT_INTERNAL` is not set. Turns out this include is not needed, so just drop it.