msm: iommu: Use iommu_map_range for 4K mappings

iommu_map_range is much more effective than
calling iommu_map for each page to be mapped.

Change-Id: I8b140a92862304c27acab7f4918b12ec3497185d
CRs-fixed: 369080
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>