Don't require a position fix before reporting Geoclue satellite info.

The Geoclue plugin uses the Geoclue master provider to select the most
appropriate position provider. However, it doesn't select a provider
unless it is in the available state. For satellite information a
position fix is not required.

If the Geoclue master provider doesn't return a valid provider the
plugin will now listen for all SatelliteChanged signals from any
org.freedesktop.Geoclue.Satellite interface. This means that if
multiple satellite based providers are active at the same time
QGeoSatelliteInfoSource will include satellite information from
both providers.

Change-Id: I257b56dc03fed51a5c4ba0023862708b9618be05
Reviewed-by: Alex Blasche <alexander.blasche@digia.com>