msm: iommu: Enable use of TTBR1 register of IOMMU

Add a new platform data in iommu devices to indicate whether ttbr1
should be used which also dictates how the address space should be
split between ttbr0 and ttbr1.

Change-Id: Iab3aac74256bd4d49f47f89e6638f014e6e539e9
Signed-off-by: Shubhraprakash Das <sadas@codeaurora.org>