msm: Allow iova address alignment specification

Some clients have specific alignment requirements for
iova addresses. Allow those requirements to be specified
via the upper bits of the flag field. Since all iommu
alignment must be at least 4k, the lower bits can specify
other options while the upper bits specify the alignment.

Change-Id: I825e8d9949ac50ecc92992e3defa3526ae81b4b7
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>