drm/msm/dpu: set geometry for iommu domain

Specify geometry for DPU iommu domain which sets
the address space for gem allocations.

Signed-off-by: Jeykumar Sankaran <jsanka@codeaurora.org>
Suggested-by: Jordan Crouse <jcrouse@codeaurora.org>
Suggested-by: Vivek Gautam <vivek.gautam@codeaurora.org>
Acked-by: Jordan Crouse <jcrouse@codeaurora.org>
Signed-off-by: Rob Clark <robdclark@gmail.com>