drm/msm/sde: expose crtc property to control sui enhancements

Add a crtc property to give user-mode the control to enable/disable
the secure-ui enhancements during the secure-ui session.

Change-Id: I968953fe80afd7c972d18a1fbdd634f1560512b8
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>