ARM: dts: genmai: Fix W=1 dtc warnings

Warning (unit_address_vs_reg): Node /memory has a reg or ranges property, but no unit name
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

arch/arm/boot/dts/r7s72100-genmai.dts

@@ -25,7 +25,7 @@ chosen {
 		stdout-path = &scif2;
 	};
 
-	memory {
+	memory@8000000 {
 		device_type = "memory";
 		reg = <0x08000000 0x08000000>;
 	};