hw/virtio/virtio-iommu: Migrate to 3-phase reset

hw/virtio/virtio-iommu: Migrate to 3-phase reset

Currently the iommu may be reset before the devices
it protects. For example this happens with virtio-net.

Let's use 3-phase reset mechanism and reset the IOMMU on
exit phase after all DMA capable devices have been
reset during the 'enter' or 'hold' phase.

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Zhenzhong Duan <zhenzhong.duan@intel.com>
Acked-by: Jason Wang <jasowang@redhat.com>
Message-Id: <20250218182737.76722-2-eric.auger@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>