SF: Support to determine if the non-virtual displays are secure

- Non virtual displays can be secure/non-secure
- Add a hook to query this info from the HWC.
- This info will be used by the clients/apps which want to present
  content only to physical displays that are secure
- HDMI is considered secure if it supports HDCP

Change-Id: I632e2fa2c8d9a75258a92043c1680fa4e05a354c