iio: imu: st_lsm6dsx: fix waitime for st_lsm6dsx i2c controller

i2c controller available in st_lsm6dsx series performs i2c slave
configuration using accel clock as trigger.
st_lsm6dsx_shub_wait_complete routine is used to wait the controller has
carried out the requested configuration. However if the accel sensor is not
enabled we should not use its configured odr to estimate a proper timeout

Fixes: c91c1c84 ("iio: imu: st_lsm6dsx: add i2c embedded controller support")
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>