dt-bindings: iio: accel: Add DT binding doc for ADXL355

Add devicetree binding document for ADXL355, a 3-Axis MEMS Accelerometer.
Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210811073027.124619-2-puranjay12@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/accel/adi,adxl355.yaml

+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/accel/adi,adxl355.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Analog Devices ADXL355 3-Axis, Low noise MEMS Accelerometer
+
+maintainers:
+  - Puranjay Mohan <puranjay12@gmail.com>
+
+description: |
+  Analog Devices ADXL355 3-Axis, Low noise MEMS Accelerometer that supports
+  both I2C & SPI interfaces
+    https://www.analog.com/en/products/adxl355.html
+
+properties:
+  compatible:
+    enum:
+      - adi,adxl355
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    minItems: 1
+    maxItems: 3
+    description: |
+      Type for DRDY should be IRQ_TYPE_EDGE_RISING.
+      Three configurable interrupt lines exist.
+
+  interrupt-names:
+    description: Specify which interrupt line is in use.
+    items:
+      enum:
+        - INT1
+        - INT2
+        - DRDY
+    minItems: 1
+    maxItems: 3
+
+  vdd-supply:
+    description: Regulator that provides power to the sensor
+
+  vddio-supply:
+    description: Regulator that provides power to the bus
+
+  spi-max-frequency: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+        #include <dt-bindings/gpio/gpio.h>
+        #include <dt-bindings/interrupt-controller/irq.h>
+        i2c {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                /* Example for a I2C device node */
+                accelerometer@1d {
+                        compatible = "adi,adxl355";
+                        reg = <0x1d>;
+                        interrupt-parent = <&gpio>;
+                        interrupts = <25 IRQ_TYPE_EDGE_RISING>;
+                        interrupt-names = "DRDY";
+                };
+        };
+  - |
+        #include <dt-bindings/gpio/gpio.h>
+        #include <dt-bindings/interrupt-controller/irq.h>
+        spi {
+                #address-cells = <1>;
+                #size-cells = <0>;
+
+                accelerometer@0 {
+                        compatible = "adi,adxl355";
+                        reg = <0>;
+                        spi-max-frequency = <1000000>;
+                        interrupt-parent = <&gpio>;
+                        interrupts = <25 IRQ_TYPE_EDGE_RISING>;
+                        interrupt-names = "DRDY";
+                };
+        };