board: amlogic: Add Odroid-N2 board support

Add a proper Odroid-N2 board support to handle the Ethernet MAC
address stored in the in-SoC eFuses.

Signed-off-by: Pascal Vizeli <pvizeli@syshack.ch>
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Tested-by: Anand Moon <linux.amoon@gmail.com>