'reg' without any constraints allows multiple items which is not the
intention for Ethernet controller's port number.
Constrain the 'reg' on AX88178 and LAN95xx USB Ethernet Controllers.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Reviewed-by: Oleksij Rempel <o.rempel@xxxxxxxxxxxxxx>