iio: imu: st_lsm6dsx: do not power-off accel if events are enabled

Do not power-off accel unconditionally if wake-up events are enabled
powering off the hw FIFO. At the same time do not power-off the accel
sensor if it is 'batched' in the hw FIFO disabling sensor events

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