ARM: dts: dra7: 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/dra7-evm.dts

@@ -16,7 +16,7 @@ / {
 	model = "TI DRA742";
 	compatible = "ti,dra7-evm", "ti,dra742", "ti,dra74", "ti,dra7";
 
-	memory {
+	memory@0 {
 		device_type = "memory";
 		reg = <0x0 0x80000000 0x0 0x60000000>; /* 1536 MB */
 	};

arch/arm/boot/dts/dra72-evm-revc.dts

@@ -11,7 +11,7 @@
 / {
 	model = "TI DRA722 Rev C EVM";
 
-	memory {
+	memory@0 {
 		device_type = "memory";
 		reg = <0x0 0x80000000 0x0 0x80000000>; /* 2GB */
 	};

arch/arm/boot/dts/dra72-evm.dts

@@ -9,7 +9,7 @@
 / {
 	model = "TI DRA722";
 
-	memory {
+	memory@0 {
 		device_type = "memory";
 		reg = <0x0 0x80000000 0x0 0x40000000>; /* 1024 MB */
 	};