msm: v4l2: use new IOMMU mapping API.

The ion_phys API is being deprecated. Instead there
is a new set of API that does the same thing as ion_phys
if the system has no IOMMU enabled. Otherwise, it
returns an IOMMU device virtual address.

Change-Id: I1f01d33cbc6d236d28c9193a90e48377b9fb35cc
Signed-off-by: Ankit Premrajka <ankitp@codeaurora.org>