iio: imu: st_lsm6dsx: reload trimming parameter at bootstrap

Perform a complete device reset at bootstrap reloading trimming parameter
after sw reset is completed. Device sw reset/boot is explained here:
https://www.st.com/resource/en/application_note/dm00517282.pdf,
section 5.7

Signed-off-by: Lorenzo Bianconi <lorenzo.bianconi@redhat.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>