amd-iommu: use correct constants in amd_iommu_get_next_table_from_pte()

amd-iommu: use correct constants in amd_iommu_get_next_table_from_pte()

...and change the name to amd_iommu_get_address_from_pte() since the
address read is not necessarily the address of a next level page table.
(If the 'next level' field is not 1 - 6 then the address is a page
address).

The constants in use prior to this patch relate to device table entries
rather than page table entries. Although they do have the same value, it
makes the code confusing to read.

This patch also changes the PDE/PTE pointer argument to void *, and
removes any u32/uint32_t casts in the call sites. Unnecessary casts
surrounding call sites are also removed.

No functional change.

NOTE: The patch also adds emacs boilerplate to iommu_map.c

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Reviewd-by: Brian Woods <brian.woods@amd.com>