Add description of the switch that is present on the RZ/N1 SoC. This
description includes ethernet-ports description for all the ports that
are present on the switch along with their connection to the MII
converter ports and to the GMAC for the CPU port.
Signed-off-by: Clément Léger <clement.leger@xxxxxxxxxxx>
Reviewed-by: Vladimir Oltean <olteanv@xxxxxxxxx>