vfio/pds: Add multi-region support

vfio/pds: Add multi-region support

Only supporting a single region/range is limiting,
wasteful, and in some cases broken (i.e. when there
are large gaps in the iova memory ranges). Fix this
by adding support for multiple regions based on
what the device tells the driver it can support.

Signed-off-by: Brett Creeley <brett.creeley@amd.com>
Signed-off-by: Shannon Nelson <shannon.nelson@amd.com>
Link: https://lore.kernel.org/r/20231117001207.2793-7-brett.creeley@amd.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>