disp: msm: dp: check for active panels ptr before cleanup

During a probable race condition where usermode is triggering
a delayed cleanup, this instance would be empty leading to a null
pointer dereference. This change will add protection around this
pointer.

Change-Id: I8e90a1ba3ca925f08678e5fa67616420204edae7
Signed-off-by: Sandeep Gangadharaiah <sandgang@codeaurora.org>

msm/dp/dp_display.c

@@ -403,7 +403,7 @@ static void dp_display_hdcp_register_streams(struct dp_display_private *dp)
 static void dp_display_hdcp_deregister_stream(struct dp_display_private *dp,
 		enum dp_stream_id stream_id)
 {
-	if (dp->hdcp.ops->deregister_streams) {
+	if (dp->hdcp.ops->deregister_streams && dp->active_panels[stream_id]) {
 		struct stream_info stream = {stream_id,
 				dp->active_panels[stream_id]->vcpi};