sunxi: dts: Pine64: add Ethernet alias

The sun8i-emac driver works fine with the A64 Ethernet IP, but we are
missing an alias entry to trigger the driver instantiation by U-Boot.
Add the line to point U-Boot to the Ethernet DT node.
This enables TFTP boot on the Pine64.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

arch/arm/dts/sun50i-a64-pine64-common.dtsi

@@ -46,6 +46,7 @@
 
 	aliases {
 		serial0 = &uart0;
+		ethernet0 = &emac;
 	};
 
 	soc {