dt-bindings:iio:health:ti,afe4403: txt to yaml binding

A few questions came up whilst converting this one.
1) What is actually required?
  - Checking Linux driver, interrupt is not, and the tx-supply could
    be supplied by a stub regulator as long as it's always on.
    As such I have reduced the required list to just compatible and reg.
2) What is the regulator called?
  - It's tx-supply in the binding doc, but the driver requests tx_sup.
    I'll post a fix patch to change the driver to fix this as it makes
    little sense.

Andrew's email is bouncing so until someone else steps up I have
listed myself as maintainer for this binding.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20201031184854.745828-8-jic23@kernel.org

Documentation/devicetree/bindings/iio/health/afe4403.txt

-Texas Instruments AFE4403 Heart rate and Pulse Oximeter
-
-Required properties:
- - compatible		: Should be "ti,afe4403".
- - reg			: SPI chip select address of device.
- - tx-supply		: Regulator supply to transmitting LEDs.
- - interrupts		: The interrupt line the device ADC_RDY pin is
-			  connected to. For details refer to,
-			  ../../interrupt-controller/interrupts.txt.
-
-Optional properties:
- - reset-gpios		: GPIO used to reset the device.
-			  For details refer to, ../../gpio/gpio.txt.
-
-For other required and optional properties of SPI slave nodes
-please refer to ../../spi/spi-bus.txt.
-
-Example:
-
-&spi0 {
-	heart_mon@0 {
-		compatible = "ti,afe4403";
-		reg = <0>;
-		spi-max-frequency = <10000000>;
-
-		tx-supply = <&vbat>;
-
-		interrupt-parent = <&gpio1>;
-		interrupts = <28 IRQ_TYPE_EDGE_RISING>;
-
-		reset-gpios = <&gpio1 16 GPIO_ACTIVE_LOW>;
-	};
-};

Documentation/devicetree/bindings/iio/health/ti,afe4403.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/health/ti,afe4403.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments AFE4403 Heart rate and Pulse Oximeter
+
+maintainers:
+  - Jonathan Cameron <jic23@kernel.org>
+
+properties:
+  compatible:
+    const: ti,afe4403
+
+  reg:
+    maxItems: 1
+
+  tx-supply:
+    description: Supply to transmitting LEDs.
+
+  interrupts:
+    maxItems: 1
+    description: Connected to ADC_RDY pin.
+
+  reset-gpios: true
+
+  spi-max-frequency: true
+
+additionalProperties: false
+
+required:
+  - compatible
+  - reg
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        heart_mon@0 {
+            compatible = "ti,afe4403";
+            reg = <0>;
+            spi-max-frequency = <10000000>;
+            tx-supply = <&vbat>;
+            interrupt-parent = <&gpio1>;
+            interrupts = <28 IRQ_TYPE_EDGE_RISING>;
+            reset-gpios = <&gpio1 16 GPIO_ACTIVE_LOW>;
+        };
+    };
+...