drm/msm/sde: use secure-direct translation for secure display

Fix the secure display usecase to use secure-direct translation.
Modify the validation checks in crtc and planes to reflect the
same. This will configure the hw pipes to fetch from the
secure domain for secure-display. As part of the change, modify
few invalid conditional checks and post-pone prepare_fb for
planes after coming out of secure-display session.

Change-Id: I41adbb8d4e2fb5d9323a61c20a09f6edbd612721
Signed-off-by: Veera Sundaram Sankaran <veeras@codeaurora.org>