disp: msm: sde: add secure session flag in sde_crtc state

This change adds a flag in sde_crtc_state to identify the
ongoing secure session. Following are the changes included
as part of this:

1) Whenever there is a direct transition from secure UI to
secure camera(&viceversa).
2) In video mode, when null commit is not present for
transition between secure camera & secure video.
3) This change also adds required wait while transitioning
from secure video session to secure camera in cmd mode.

Change-Id: If9a70fa04b70b03315efe8db1a283faa6d32055b
Signed-off-by: Yashwanth <yvulapu@codeaurora.org>