iommu/virtio: Return size mapped for a detached domain

iommu/virtio: Return size mapped for a detached domain

When map() is called on a detached domain, the domain does not exist in
the device so we do not send a MAP request, but we do update the
internal mapping tree, to be replayed on the next attach. Since this
constitutes a successful iommu_map() call, return *mapped in this case
too.

Fixes: 7e62edd7a33a ("iommu/virtio: Add map/unmap_pages() callbacks implementation")
Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20230515113946.1017624-3-jean-philippe@linaro.org
Signed-off-by: Joerg Roedel <jroedel@suse.de>