hammerhead: usb networking is broken

I'm about to merge !450 (merged), which updates the kernel to 5.2_rc3, and fixes xorg and wayland (#221 (closed)). We could not get usb networking going with this version yet.

@MartijnBraam added verbose logging to the networking !468 (merged), which can be read out by UART. Right now it runs into "Could not find an interface to run a dhcp server on" here, see the output in the top post of !468 (merged). He wrote in !450 (comment 186042906):

The current issue with usb networking is that there's no usb device controller in /sys/class/udc, maybe @masneyb knows what's going wrong with that?

CC: @MartijnBraam, @masneyb, @pparent, @minlexx, @julian-goldsmith, @unrznbl, @bshah