usb gadget functionality, iio activate property and a couple fixes
Created by: brgl
This PR adds the usbnet functionality to acme. It also adds the iio activate property to the probes and fixes a couple of issues. ACME now advertises itself over avahi using the _baylibre_acme._tcp service type.
Network problems fixed:
- udhcpd startup
- ethernet configuration with the cable disconnected (kernel was hanging on dhcp)