Current description for proximity measurement is ambiguous. While
the first part says that proximity is measured by observing
reflectivity, the second part incorrectly infers that reported values
should behave like a distance.

This is because of AS3935 lightning sensor which uses the proximity
API, while not being a true proximity sensor.

Note this is marked for stable as it accompanies a fix in ABI usage
to the sx9500 driver which would otherwise appear to be correct.

Fixes:  614e8842 ("iio: ABI: add clarification for proximity")
Signed-off-by: Daniel Baluta <daniel.baluta@intel.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>