iommu/arm-smmu: Add support for split page table domains

There are IOMMU domains that require use of both the upper and
lower portions of the IOVA space. To fulfill this requirement,
add support to the ARM SMMU driver to correctly configure a few
registers when initializing a context bank, as well as use the
correct set of page tables when handling IOVAs.

Change-Id: I9845354845495601de83bf946c96c36f2346ceb7
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>