iio: cros_ec: set calibscale for 3d MEMS to unit vector

By default, set the calibscale vector to unit vector.
When calibrating one axis, the other axis calibrations  are sent as well.
If left to 0, sensor data from uncalibrated axis are zero'ed out until
all axis are calibrated.

Fixes: ed1f2e85 ("iio: cros_ec: Add calibscale for 3d MEMS ")
Signed-off-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>