vfio: Collect container iova range info

vfio: Collect container iova range info

Collect iova range information if VFIO_IOMMU_TYPE1_INFO_CAP_IOVA_RANGE
capability is supported.

This allows to propagate the information though the IOMMU MR
set_iova_ranges() callback so that virtual IOMMUs
get aware of those aperture constraints. This is only done if
the info is available and the number of iova ranges is greater than
0.

A new vfio_get_info_iova_range helper is introduced matching
the coding style of existing vfio_get_info_dma_avail. The
boolean returned value isn't used though. Code is aligned
between both.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Alex Williamson <alex.williamson@redhat.com>
Tested-by: Yanghang Liu <yanghliu@redhat.com>
Signed-off-by: Cédric Le Goater <clg@redhat.com>