ARM: dts: vfxxx: Move nodes which have no reg property out of bus

Move iio-hwmon node from soc node to root node.

iio-hwmon node does not have any register properties and thus
shouldn't be placed on the bus.

This fixes the following build warnings with W=1:

arch/arm/boot/dts/vf500-colibri-eval-v3.dtb: Warning (simple_bus_reg): Node /soc/iio-hwmon missing or empty reg/ranges property

Based on a patch from Simon Horman for the renesas r8a7795 dtsi.
Signed-off-by: NFabio Estevam <fabio.estevam@nxp.com>
Signed-off-by: NShawn Guo <shawnguo@kernel.org>

arch/arm/boot/dts/vfxxx.dtsi

@@ -84,6 +84,11 @@
 		mask = <0x1000>;
 	};
 
+	iio-hwmon {
+		compatible = "iio-hwmon";
+		io-channels = <&adc0 16>, <&adc1 16>;
+	};
+
 	soc {
 		#address-cells = <1>;
 		#size-cells = <1>;
@@ -762,10 +767,5 @@
 				status = "disabled";
 			};
 		};
-
-		iio-hwmon {
-			compatible = "iio-hwmon";
-			io-channels = <&adc0 16>, <&adc1 16>;
-		};
 	};
 };