Add support to STM LSM6DSO 6-axis IMU sensor driver.
This driver supports communication with device though both
I2C and SPI bus and both polling and drdy trigger mode.
This driver supports also the sensorhub mode with the possibility
to connect a maximum of two external devices, typically a
magnetometer and an environmental sensor, currently selected among
following devices: lis2mdl magnetometer, lps22hh or lps22hb
pressure and temperature sensors, HTS221 humidity sensor.
Signed-off-by: Armando Visconti <armando.visconti@st.com>