arm64: dts: rockchip: rk1808: Add ethernet alias for uboot write MAC address

Now we use U-Boot to write the MAC address into DTB, to
solve the problem of getting the MAC address in the vendor
partition too late at the kernel level, so the Ethernet
alias is added for U-Boot to quickly find the gmac DTB node.

Signed-off-by: David Wu <david.wu@rock-chips.com>
Change-Id: Ie7ec87208811e2fd7a217558d97e0f1bd46d122d

arch/arm64/boot/dts/rockchip/rk1808.dtsi

@@ -21,6 +21,7 @@
 	#size-cells = <2>;
 
 	aliases {
+		ethernet0 = &gmac;
 		i2c0 = &i2c0;
 		i2c1 = &i2c1;
 		i2c2 = &i2c2;