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.nl


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>