framepositionner: Fix the range of properties dealing with number of pixels
framepositionner: Fix the range of properties dealing with number of pixels

This way it is possible to interpolate those values.

cfoch/ges,cfoch/gst-editing-services,cfoch/ges,cfoch/ges,cfoch/ges,cfoch/gst-editing-services,cfoch/gst-editing-services,cfoch/gst-editing-services