Set dataRates for sensors

Some sensors need to set a dataRate in which they are providing values.

Values are in Hz, hence the conversion and defaults to 1Hz like on other
backends as well.

Task-number: QTBUG-40664
Change-Id: I980155f9b4b2772e8420df4b51e8ebb5cdea6037
Reviewed-by: Andrew Knight <andrew.knight@digia.com>