BlackBerry: Disabled "returnGeoValues" feature

Elimination of interference is not supported on BlackBerry, so
returnGeoValues property will be ignored.
This is a backport of QtSensors commit 6348938.

Change-Id: I77718fbe9a100f9f16007095f52c73e9e7db62ac
Reviewed-by: Thomas McGuire <thomas.mcguire@kdab.com>