mips: dts: loongson: fix DTC unit name warnings

Fixes the following W=1 kernel build warning(s):
arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi:26.9-32.4: Warning (unit_address_vs_reg): /memory: node has a reg or ranges property, but no unit name
Signed-off-by: zhaoxiao <zhaoxiao@uniontech.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>

arch/mips/boot/dts/loongson/loongson64-2k1000.dtsi

@@ -23,7 +23,7 @@ cpu0: cpu@0 {
 		};
 	};
 
-	memory {
+	memory@200000 {
 		compatible = "memory";
 		device_type = "memory";
 		reg = <0x00000000 0x00200000 0x00000000 0x0ee00000>, /* 238 MB at 2 MB */