ARM: dts: mmp2: give gpio node a name

This will be useful for boards that actually use GPIO pins.
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/mmp2.dtsi

@@ -168,7 +168,7 @@ uart4: uart@d4016000 {
 				status = "disabled";
 			};
 
-			gpio@d4019000 {
+			gpio: gpio@d4019000 {
 				compatible = "marvell,mmp2-gpio";
 				#address-cells = <1>;
 				#size-cells = <1>;