dt-bindings: iio: st-sensors: Add LSM303C accelerometer+magnetometer

The ST LSM303C [1] is a accelerometer and magnetometer combo sensor
compatible with the existing ST sensor bindings. Accelerometer and
magnetometer are exposed through separate I2C/SPI devices, so document
separate compatibles with -accel and -magn suffix.

[1]: https://www.st.com/resource/en/datasheet/lsm303c.pdf



Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Acked-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230106102239.9647-2-stephan@gerhold.net


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