iommu/virtio: Sort reserved regions

To ease identity mapping support, keep the list of reserved regions
sorted.

Reviewed-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/20211201173323.1045819-4-jean-philippe@linaro.org


Signed-off-by: Joerg Roedel <jroedel@suse.de>