ARM: tegra: Fix ethernet node names

The node name of Ethernet controller should be "ethernet" instead of
"asix" or "smsc" as required by Ethernet controller devicetree schema:

    Documentation/devicetree/bindings/net/ethernet-controller.yaml

This patch can potentially affect boot loaders patching against full
node path instead of using device aliases.

Signed-off-by: Oleksij Rempel <o.rempel@pengutronix.de>
Signed-off-by: Thierry Reding <treding@nvidia.com>