The inferior calls to rowCount() and columnCount() used to create
the "n x m" "nice" display are troublesome when debugging an actual
issue with item models and not too helpful otherwise. People needing
that information can still evaluate m->rowCount() etc manually.

Change-Id: I3a3feed6aab19096ab01bc91c488de5fcbd732d7
Reviewed-by: Christian Stenger <christian.stenger@qt.io>