ARM: dts: mmp3-dell-ariel: Add a name to /memory node

Ponted out by DTC:

  <stdout>: Warning (unit_address_vs_reg): /memory: node has a reg or ranges
  property, but no unit name

Link: https://lore.kernel.org/r/20191031163455.1711872-4-lkundrak@v3.skSigned-off-by: Lubomir Rintel <lkundrak@v3.sk>
Signed-off-by: Olof Johansson <olof@lixom.net>

arch/arm/boot/dts/mmp3-dell-ariel.dts

@@ -21,7 +21,7 @@ chosen {
 		bootargs = "earlyprintk=ttyS2,115200 console=ttyS2,115200";
 	};
 
-	memory {
+	memory@0 {
 		linux,usable-memory = <0x0 0x7f600000>;
 		available = <0x7f700000 0x7ff00000 0x00000000 0x7f600000>;
 		reg = <0x0 0x80000000>;