ARM: dts: omap2: Add missing unit name to memory nodes

This patch fixes the following DTC warnings:

"Node /memory has a reg or ranges property, but no unit name"
Signed-off-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/omap2420-h4.dts

@@ -13,7 +13,7 @@ / {
 	model = "TI OMAP2420 H4 board";
 	compatible = "ti,omap2420-h4", "ti,omap2420", "ti,omap2";
 
-	memory {
+	memory@80000000 {
 		device_type = "memory";
 		reg = <0x80000000 0x4000000>; /* 64 MB */
 	};

arch/arm/boot/dts/omap2420-n8x0-common.dtsi

 #include "omap2420.dtsi"
 
 / {
-	memory {
+	memory@80000000 {
 		device_type = "memory";
 		reg = <0x80000000 0x8000000>; /* 128 MB */
 	};

arch/arm/boot/dts/omap2430-sdp.dts

@@ -13,7 +13,7 @@ / {
 	model = "TI OMAP2430 SDP";
 	compatible = "ti,omap2430-sdp", "ti,omap2430", "ti,omap2";
 
-	memory {
+	memory@80000000 {
 		device_type = "memory";
 		reg = <0x80000000 0x8000000>; /* 128 MB */
 	};