ARM: dts: ls1021a: add reboot node to .dtsi

The LS1021A can be reset via the dcfg regmap in the same way as the
arm64 layerscape SoCs, so add the corresponding DT node.
Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/ls1021a.dtsi

@@ -108,6 +108,13 @@ pmu {
 			     <GIC_SPI 139 IRQ_TYPE_LEVEL_HIGH>;
 	};
 
+	reboot {
+		compatible = "syscon-reboot";
+		regmap = <&dcfg>;
+		offset = <0xb0>;
+		mask = <0x02>;
+	};
+
 	soc {
 		compatible = "simple-bus";
 		#address-cells = <2>;