net: ethernet: Align Ethernet drivers/L2 with iface state upgrade

Align Ethernet/Wi-Fi drivers/L2 with interface state handling update.

For drivers, that did not support carrier detection, no changes are
needed.

Driver that did support carrier detection, are updated to set the
carrier state to OFF by default, instead of setting the
NET_IF_NO_AUTO_START flag. This allows to postopne the actual
NET_EVENT_IF_UP notification until driver detects that carrier is ready.

Signed-off-by: Robert Lubos <robert.lubos@nordicsemi.no>