'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@linaro.org>
Reviewed-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Rob Herring <robh@kernel.org>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>