The table offset is in entries, each of which imply a dma address of
an IOMMU page.

Also, we should check the device can reach the whole IOMMU table.
Signed-off-by: NMilton Miller <miltonm@bga.com>
Signed-off-by: NNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>