arm: zynq: Add missing address node name in microzed board

This patch is fixing issue reported by dtc:
arch/arm/boot/dts/zynq-microzed.dtb: Warning (unit_address_vs_reg): Node
/memory has a reg or ranges property, but no unit name
Signed-off-by: Michal Simek <michal.simek@xilinx.com>

arch/arm/boot/dts/zynq-microzed.dts

@@ -15,7 +15,7 @@ aliases {
 		serial0 = &uart1;
 	};
 
-	memory {
+	memory@0 {
 		device_type = "memory";
 		reg = <0x0 0x40000000>;
 	};