arm: mvebu: armada-388-gp.dts: Add ethernet aliases

Adding these aliases enables the update of the MAC addresses from
within U-Boot.
Signed-off-by: NStefan Roese <sr@denx.de>
Cc: Luka Perkov <luka.perkov@sartura.hr>

arch/arm/dts/armada-388-gp.dts

@@ -52,6 +52,8 @@
 	};
 
 	aliases {
+		ethernet0 = &eth0;
+		ethernet1 = &eth1;
 		spi0 = &spi0;
 	};