vhost-vdpa: Add support for vIOMMU.

vhost-vdpa: Add support for vIOMMU.

1. The vIOMMU support will make vDPA can work in IOMMU mode. This
will fix security issues while using the no-IOMMU mode.
To support this feature we need to add new functions for IOMMU MR adds and
deletes.

Also since the SVQ does not support vIOMMU yet, add the check for IOMMU
in vhost_vdpa_dev_start, if the SVQ and IOMMU enable at the same time
the function will return fail.

2. Skip the iova_max check vhost_vdpa_listener_skipped_section(). While
MR is IOMMU, move this check to vhost_vdpa_iommu_map_notify()

Verified in vp_vdpa and vdpa_sim_net driver

Signed-off-by: Cindy Lu <lulu@redhat.com>
Message-Id: <20230510054631.2951812-5-lulu@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>