msm: mdss: handle secure display state for MDP

Secure display state is MDP hardware state instead of
individual interface state. All interfaces should push
only secure content data when MDP hardware is in secure state.
All non-secure content should be rejected to avoid XPU
violation. DSI hardware should also avoid DCS command
communication in this state to avoid non-secure VBIF access.

CRs-fixed: 686451
Change-Id: I3beb6c24361e3c42e18107d2a2ebebafc5da1b52
Signed-off-by: Dhaval Patel <pdhaval@codeaurora.org>