dt-bindings: iio: accel: Add bmi088 accelerometer bindings

This adds the device-tree bindings for the Bosch Sensortec BMI088 IMU,
the accelerometer part.
Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210125150732.23873-1-mike.looijmans@topic.nlSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/accel/bosch,bmi088.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/iio/accel/bosch,bmi088.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Bosch BMI088 IMU accelerometer part
+
+maintainers:
+  - Mike Looijmans <mike.looijmans@topic.nl>
+
+description: |
+  Acceleration part of the IMU sensor with an SPI interface
+  Specifications about the sensor can be found at:
+    https://www.bosch-sensortec.com/media/boschsensortec/downloads/datasheets/bst-bmi088-ds001.pdf
+
+properties:
+  compatible:
+    enum:
+      - bosch,bmi088-accel
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency: true
+
+  vdd-supply: true
+
+  vddio-supply: true
+
+  interrupts:
+    minItems: 1
+    maxItems: 2
+    description: |
+      Type should be either IRQ_TYPE_LEVEL_HIGH or IRQ_TYPE_LEVEL_LOW.
+      Two configurable interrupt lines exist.
+
+  interrupt-names:
+    description: Specify which interrupt line is in use.
+    items:
+      enum:
+        - INT1
+        - INT2
+    minItems: 1
+    maxItems: 2
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+      #address-cells = <1>;
+      #size-cells = <0>;
+      bmi088-accel@1 {
+        compatible = "bosch,bmi088-accel";
+        reg = <1>;
+        spi-max-frequency = <10000000>;
+        interrupt-parent = <&gpio6>;
+        interrupts = <19 IRQ_TYPE_LEVEL_LOW>;
+        interrupt-names = "INT2";
+      };
+    };
+...