ia64, iommu: Add a dummy iommu_table.h file in IA64.

We don't need a complex IOMMU dependency list on IA64 so
we just define the IOMMU_* macro which is used the DMAR driver, as a dummy.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
LKML-Reference: <1286564028-2352-2-git-send-email-konrad.wilk@oracle.com>
Reported-by: Tony Luck <tony.luck@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>