iio: imu: st_lsm6dsx: drop huge include in sensor-hub driver

iio: imu: st_lsm6dsx: drop huge include in sensor-hub driver

st_lsm6dsx is a standalone driver for STM IMU sensors and does not rely
on st_sensor common framework, so it does not include st_sensor common
definitions.
In st_lsm6dsx_shub driver st_sensors.h is used just to introduce the
default wai address for LIS3MDL sensor.
Drop this largely unconnected include file and introduce the default wai
address for LIS3MDL in st_lsm6dsx_ext_dev_settings register map

Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>