ARM: dts: omap3/4/5: fix ethernet node name for different OMAP boards

The node name of Ethernet controller should be "ethernet" instead of
"usbether" 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>
Message-Id: <20220216074927.3619425-8-o.rempel@pengutronix.de>
Signed-off-by: Tony Lindgren <tony@atomide.com>