ARM: dts: armada-38x: add reference to ETH connectors for A385-AP

This commit adds some comments to the Armada 385 AP Device Tree
description to indicate which Ethernet interface matches which
physical connector on the board.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>