iio: imu: st_lsm6dsx: move decimator info in st_lsm6dsx_sensor_settings

Move FIFO decimator info in st_lsm6dsx_sensor_settings list since
decimator registers are exported in register map just in
lsm6ds3/lsm6ds3h/lsm6dsl/lsm6dsm sensors and not in other compliant
devices

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@st.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
3 files changed