gralloc/qdMetadata: Add mapSecureBuffer field to metadata struct

- The client sets this metadata to inform GPU to map the CP buffer
- GPU will check the PRIV_FLAG_SECURE and this metadata to map the CP buffer
- If this field is not set on the buffer handle, then GPU will not map
  the CP buffer
- Allow mapping of metadata for SECURE_BUFFERS also

Change-Id: I86300a1b4e3008f9d0884940420e9036c47a016f
3 files changed