dt-bindings: iio: adc: Add TI ADS1100 and ADS1000

The ADS1100 is a 16-bit ADC (at 8 samples per second).
The ADS1000 is similar, but has a fixed data rate.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20230307065535.7927-1-mike.looijmans@topic.nlSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/ti,ads1100.yaml

+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/adc/ti,ads1100.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI ADS1100/ADS1000 single channel I2C analog to digital converter
+
+maintainers:
+  - Mike Looijmans <mike.looijmans@topic.nl>
+
+description: |
+  Datasheet at: https://www.ti.com/lit/gpn/ads1100
+
+properties:
+  compatible:
+    enum:
+      - ti,ads1100
+      - ti,ads1000
+
+  reg:
+    maxItems: 1
+
+  vdd-supply: true
+
+  "#io-channel-cells":
+    const: 0
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+        adc@49 {
+            compatible = "ti,ads1100";
+            reg = <0x49>;
+        };
+    };
+...