iommu/virtio: Reverse arguments to list_add

Elsewhere in the file, there is a list_for_each_entry with
&vdev->resv_regions as the second argument, suggesting that
&vdev->resv_regions is the list head.  So exchange the
arguments on the list_add call to put the list head in the
second argument.

Fixes: 2a5a3148

 ("iommu/virtio: Add probe request")
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>

Reviewed-by: Jean-Philippe Brucker <jean-philippe@linaro.org>
Link: https://lore.kernel.org/r/1588704467-13431-1-git-send-email-Julia.Lawall@inria.fr


Signed-off-by: Joerg Roedel <jroedel@suse.de>