iommu: msm: Add call to set maximum mapped size

In some cases, the secure world needs a hint as to the maximum
amount of memory that will ever be mapped. This is necessary to
optimize data structures in the secure world. Add a call to the
secure world to indicate the maximum mapped size.

Change-Id: I8d07ec2288e37057ff96777c96ed0680f75185f3
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>