vfio/type1: Add IOVA range capability support

This allows the user-space to retrieve the supported IOVA
range(s), excluding any non-relaxable reserved regions. The
implementation is based on capability chains, added to
VFIO_IOMMU_GET_INFO ioctl.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Reviewed-by: Eric Auger <eric.auger@redhat.com>
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>