hwcomposer: In Mdss,secure content policy applies to layer buffer

In Mdss, mSecureMode is never set, instead the secure content flag
has been set/unset on each layer buffer.

Change-Id: I3283533c11206e189ce70dbc84776b2cff3a909d
diff --git a/libhwcomposer/hwc_utils.h b/libhwcomposer/hwc_utils.h
index 0005582..5316347 100644
--- a/libhwcomposer/hwc_utils.h
+++ b/libhwcomposer/hwc_utils.h
@@ -130,6 +130,7 @@
 void calculate_crop_rects(hwc_rect_t& crop, hwc_rect_t& dst,
         const int fbWidth, const int fbHeight, int orient);
 bool isSecuring(hwc_context_t* ctx);
+bool isSecureModePolicy(int mdpVersion);
 bool isExternalActive(hwc_context_t* ctx);
 
 //Helper function to dump logs