ARM: dts: armada-370-xp: Remove skeleton.dtsi

The skeleton.dtsi file was removed in ARM64 for different reasons as
explained in commit ("3ebee5a2e141 arm64: dts: kill skeleton.dtsi").

These also applies to ARM and it will also allow to get rid of the
following DTC warnings in the future:

"Node /memory has a reg or ranges property, but no unit name"

Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>

arch/arm/boot/dts/armada-xp.dtsi

@@ -53,6 +53,9 @@
 #include "armada-370-xp.dtsi"
 
 / {
+	#address-cells = <2>;
+	#size-cells = <2>;
+
 	model = "Marvell Armada XP family SoC";
 	compatible = "marvell,armadaxp", "marvell,armada-370-xp";