video: msm: wfd: Add ion_phys changes for secure session

Perform ion_phys instead of ion_map_iommu() to get physical address
for a secure session. This is a CP 2.0 requirement.

Change-Id: I080707bb272ac572ab33b40dcf67f54aea429585
CRs-fixed: 380161
Signed-off-by: Arun Menon <menon@codeaurora.org>