iommu: msm_iommu_sec: Add support for the new scm_call2 API

The scm library has added support for a new secure world
interface that is more aligned to the ARMv8 SMC calling
convention. Use the new API while maintaining backward
compatibility.

Change-Id: Ib2a52aebf28ff4cb215d0726822411dde0c075ab
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>