vfio/common: Add helper to consolidate iova/end calculation

vfio/common: Add helper to consolidate iova/end calculation

In preparation to be used in device dirty tracking, move the code that
calculate a iova/end range from the container/section.  This avoids
duplication on the common checks across listener callbacks.

Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20230307125450.62409-9-joao.m.martins@oracle.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>