board: amlogic: vim3: fix setup ethernet mac from efuse

Fix reading built-in ethernet MAC address from efuse

NOTE: MAC is stored in ASCII format, 1bytes = 2characters by 0 offset

if mac from efuse not valid we use meson_generate_serial_ethaddr

NOTE: remake odroid-n2.c from Neil Armstrong <narmstrong@baylibre.com>

Signed-off-by: Artem Lapkin <art@khadas.com>
[narmstrong: remove MAC print & spurious new endline]
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>