UPSTREAM: drm/virtio: add iommu support.

Use the dma mapping api and properly add iommu mappings for
objects, unless virtio is in iommu quirk mode.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Dave Airlie <airlied@redhat.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20180829122026.27012-3-kraxel@redhat.com


(cherry picked from commit a3b815f09bb846255c458c181b8a5b1cc66891b4)
Signed-off-by: Greg Hartman <ghartman@google.com>
BUG: 139386237
Change-Id: Iaddec4e040620ef7214f7a6c714a5d6032dd89b4