iio: accel: yamaha-yas530: Add DT bindings

iio: accel: yamaha-yas530: Add DT bindings

This adds device tree bindings for the Yamaha YAS530
family of magnetometers/compass sensors.

Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Rob Herring <robh@kernel.org>
Cc: devicetree@vger.kernel.org
Cc: phone-devel@vger.kernel.org
Cc: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Jonathan Bakker <xc-racer2@live.ca>
Link: https://lore.kernel.org/r/20201224120820.1120099-1-linus.walleij@linaro.org
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>