iommu: arm-smmu: Standardize deep pre-fetch errata workaround

Some hardware revision might have the deep prefetch bug where
invalid entries in the prefetch window would cause improper
permissions to be cached for the valid entries in this window.
Enable the workaround on such hardware by aligning the start
and end of all mapped buffers to prefetch size boundary.

Change-Id: Ib9ffd84d6e30087baabef35781e74d0544856233
Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>