hisi_acc_vfio_pci: Enable PRE_COPY flag

Now that we have everything to support the PRE_COPY state,
enable it.

Signed-off-by: Shameer Kolothum <shameerali.kolothum.thodi@huawei.com>
Link: https://lore.kernel.org/r/20221123113236.896-5-shameerali.kolothum.thodi@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>