Revert "vfio: Avoid disabling and enabling vectors repeatedly in VFIO migration"

Revert "vfio: Avoid disabling and enabling vectors repeatedly in VFIO migration"

Commit ecebe53fe993 ("vfio: Avoid disabling and enabling vectors
repeatedly in VFIO migration") avoids inefficiently disabling and
enabling vectors repeatedly and lets the unmasked vectors be enabled
one by one.

But we want to batch multiple routes and defer the commit, and only
commit once outside the loop of setting vector notifiers, so we
cannot enable the vectors one by one in the loop now.

Revert that commit and we will take another way in the next patch,
it can not only avoid disabling/enabling vectors repeatedly, but
also satisfy our requirement of defer to commit.

Signed-off-by: Longpeng(Mike) <longpeng2@huawei.com>
Link: https://lore.kernel.org/r/20220326060226.1892-5-longpeng2@huawei.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>