iommu: fix order of arguments in iommu_map call at iommu_hwdom_init

iommu: fix order of arguments in iommu_map call at iommu_hwdom_init

The order of the page_order and the flags parameters are inverted in
the call to iommu_map made in iommu_hwdom_init.

Fixes: e8afe1124cc1 ("iommu: elide flushing for higher order map/unmap operations")
Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Release-acked-by: Juergen Gross <jgross@suse.com>