msm: camera: smmu: Add API to return memory region information

Add a new API in camera SMMU driver to return memory region
information to client drivers. This is useful for client drivers
to know the layout of their own IOVA space. This IOVA space is
managed by the camera SMMU driver on behalf of client drivers.

CRs-Fixed: 1108641
Change-Id: I2664f7b8f6959525de9ac5d0764fa15f7e4e277a
Signed-off-by: Seemanta Dutta <seemanta@codeaurora.org>