Converted USB Host CDC-ECM to a lower half driver.
Removed existing full network driver callbacks and replaced with lower
half.
Signed-off-by: daniellizewski <daniellizewski@geotab.com>
Added support for USB host to use an USB CDC-ECM device.
This class is used for usb-ethernet adapters as well as many modems.
Signed-off-by: daniellizewski <daniellizewski@geotab.com>