msm: iommu: Add support for updating mask register for smmu

For some of the smmus's the number of unique stream
ids is more than the number of Stream Mapping
Table entries. The mask field of the SMRn register
needs to updated to handle the correct mapping
behaviour.

Change-Id: I72a2ffe538a6078320c65575d1b007e4114401a4
Signed-off-by: Neeti Desai <neetid@codeaurora.org>