liboverlay: Enable secure content flag in Mdss Rotator.

- Secured contents shared with hardware should be uncached.
- Secure heap needs to be contiguously allocated & aligned to 1MB,
  which is not supported by IOMMU heap.

Change-Id: I6c7c00d5363319f9a6db6e52c1e78e1b16ecd9aa
2 files changed