iommu: msm: use phys_addr_t for PA in secure mapping

current implementation uses unsigned int to store physcial address.
In case of system with > 4GB physical memory address will truncate.
Using phys_addr_t fixes the same.

Change-Id: I24df65f74fd464de86f227315dabee4e89d4fa32
Signed-off-by: Prakash Gupta <guptap@codeaurora.org>