dt-bindings:iio:adc:nxp,lpc1850-adc yaml conversion

Most of the description in the original doc is effectively boilerplate
and does not bring much value so I have not carried it over into the yaml.

Added #io-channel-cells to simplify use of channels on this ADC by
consumer drivers.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: Joachim Eastwood <manabian@gmail.com>
Link: https://lore.kernel.org/r/20200909175946.395313-10-jic23@kernel.org

Documentation/devicetree/bindings/iio/adc/lpc1850-adc.txt

-NXP LPC1850 ADC bindings
-
-Required properties:
-- compatible: Should be "nxp,lpc1850-adc"
-- reg: Offset and length of the register set for the ADC device
-- interrupts: The interrupt number for the ADC device
-- clocks: The root clock of the ADC controller
-- vref-supply: The regulator supply ADC reference voltage
-- resets: phandle to reset controller and line specifier
-
-Example:
-
-adc0: adc@400e3000 {
-	compatible = "nxp,lpc1850-adc";
-	reg = <0x400e3000 0x1000>;
-	interrupts = <17>;
-	clocks = <&ccu1 CLK_APB3_ADC0>;
-	vref-supply = <&reg_vdda>;
-	resets = <&rgu 40>;
-};

Documentation/devicetree/bindings/iio/adc/nxp,lpc1850-adc.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/nxp,lpc1850-adc.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: NXP LPC1850 ADC bindings
+
+maintainers:
+  - Joachim Eastwood <manabian@gmail.com>
+
+description:
+  Supports the ADC found on the LPC1850 SoC.
+
+properties:
+  compatible:
+    const: nxp,lpc1850-adc
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 1
+
+  vref-supply: true
+
+  resets:
+    maxItems: 1
+
+  "#io-channel-cells":
+    const: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+  - vref-supply
+  - resets
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/lpc18xx-ccu.h>
+    soc {
+        #address-cells = <1>;
+        #size-cells = <1>;
+        adc@400e3000 {
+            compatible = "nxp,lpc1850-adc";
+            reg = <0x400e3000 0x1000>;
+            interrupts = <17>;
+            clocks = <&ccu1 CLK_APB3_ADC0>;
+            vref-supply = <&reg_vdda>;
+            resets = <&rgu 40>;
+         };
+    };
+...