ARM: dts: mmp3-dell-ariel: Add a serial point alias

Make sure UART3, where the console is, is called ttyS2. That is
consistent with the early console.

Link: https://lore.kernel.org/r/20191031163455.1711872-5-lkundrak@v3.sk
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/mmp3-dell-ariel.dts

@@ -14,6 +14,10 @@
 	model = "Dell Ariel";
 	compatible = "dell,wyse-ariel", "marvell,mmp3";
 
+	aliases {
+		serial2 = &uart3;
+	};
+
 	chosen {
 		#address-cells = <0x1>;
 		#size-cells = <0x1>;