Enable OTG port as CDC ETH for console output using netconsole.

1. Added DHCPSERVER functionality in u-boot to auto configure network.
2. Enabled CDC ETH OTG
3. Added automatic CDC ETH console if OTG cable connected on boot.
4. Added script tools/nc.odroid for automatic netconsole.

The Odroid is configured with IP 10.10.10.11 and the other end is DHCP
served an address of 10.10.10.10.
Signed-off-by: Suriyan Ramasami <suriyan.r@gmail.com>

The steps to get console over the OTG port is as follows:
1. Power off Odroid
2. Connect OTG port with cable to USB host
3. In host ensure firewall is not blocking port 6666 and DHCP ports
   67 and 68. All are UDP.
4. In host ensure automatic configuration of ethernet interface is turned
   on in Network Manager. Its usually enabled by default. On the host
   it will appear as interface usb0
5. Run tools/nc.odroid
6. Power on Odroid board.