ARM: dts: armada-375: Fixup memory DT warning

memory has a reg property so the unit name should contain an address.
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/boot/dts/armada-375-db.dts

@@ -58,7 +58,7 @@ chosen {
 		stdout-path = "serial0:115200n8";
 	};
 
-	memory {
+	memory@0 {
 		device_type = "memory";
 		reg = <0x00000000 0x40000000>; /* 1 GB */
 	};