iio: imu: st_lsm6dsx: grab conf mutex in st_lsm6dsx_write_event_config

Always grub conf mutex in st_lsm6dsx_write_event_config since it can run
concurrently with FIFO configuration

Fixes: b5969abf ("iio: imu: st_lsm6dsx: add motion events")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/imu/st_lsm6dsx/st_lsm6dsx_core.c

@@ -1619,7 +1619,9 @@ static int st_lsm6dsx_write_event_config(struct iio_dev *iio_dev,
 	if (err < 0)
 		return err;
 
+	mutex_lock(&hw->conf_lock);
 	err = st_lsm6dsx_sensor_set_enable(sensor, state);
+	mutex_unlock(&hw->conf_lock);
 	if (err < 0)
 		return err;