pSeries p615 happens to have a bus hierarchy where the IDE controller for
the built-in CD is connected directly to the PHB without an intermediate
EADS bridge.  The new iommu/bus setup code assumed that all systems with
EADS will have all devices under them, so this resulted in the IDE
controller not having an iommu table allocated.

To avoid this, always allocate a small table at the PHB level.  It will
never be used for regular devices, and it's allocated out of the 256MB that
we previously skipped.
Signed-off-by: Olof Johansson <olof@austin.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>