iommu / p2m: add a page_order parameter to iommu_map/unmap_page()...

iommu / p2m: add a page_order parameter to iommu_map/unmap_page()...

...and re-name them to iommu_map/unmap() since they no longer necessarily
operate on a single page.

The P2M code currently contains many loops to deal with the fact that,
while it may be require to handle page orders greater than 0, the
IOMMU map and unmap functions do not.
This patch adds a page_order parameter to those functions and implements
the necessary loops within. This allows the P2M code to be substantially
simplified.

This patch also adds emacs boilerplate to xen/iommu.h to avoid tabbing
problem.

NOTE: This patch does not modify the underlying vendor IOMMU
      implementations to deal with more than a single page at once.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: George Dunlap <george.dunlap@citrix.com>