Clean up the intel-iommu code related to deferred iommu flush logic. There is
no need to allocate all the iommu's as a sequential array.

This will be used later in the interrupt-remapping patch series to
allocate iommu much early and individually for each device remapping
hardware unit.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: akpm@linux-foundation.org
Cc: arjan@linux.intel.com
Cc: andi@firstfloor.org
Cc: ebiederm@xmission.com
Cc: jbarnes@virtuousgeek.org
Cc: steiner@sgi.com
Signed-off-by: NIngo Molnar <mingo@elte.hu>