dt-bindings: iio: accel: adxl380: add new supported parts

dt-bindings: iio: accel: adxl380: add new supported parts

Include ADXL318 and ADXL319 accelerometers to the documentation.
The ADXL318 is based on the ADXL380, while the ADXL319 is based on the
ADXL382. However, the ADXL318/319 do not support some built-in features
like single tap, double tap and triple tap detection, and also activity
and inactivity detection.

Signed-off-by: Jonathan Santos <Jonathan.Santos@analog.com>
Acked-by: Krzysztof Kozlowski <krzk@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>