disp: msm: dp: clear MST sim context during DP sim disable

After freeing MST sim context memory the pointer isn't set
to NULL leading to unauthorized memory access. Along with
this fix, this change also defers checking sim device ports
pointer at a more appropriate place in the function call.

Change-Id: I20c09edbd454c9d491060815dc73bae34aab6b08
Signed-off-by: Sandeep Gangadharaiah <quic_sandgang@quicinc.com>

msm/dp/dp_debug.c

@@ -74,19 +74,18 @@ static int dp_debug_attach_sim_bridge(struct dp_debug_private *debug)
 {
 	int ret;
 
-	if (debug->sim_bridge)
-		return 0;
+	if (!debug->sim_bridge) {
+		ret = dp_sim_create_bridge(debug->dev, &debug->sim_bridge);
+		if (ret)
+			return ret;
 
-	ret = dp_sim_create_bridge(debug->dev, &debug->sim_bridge);
-	if (ret)
-		return ret;
+		if (debug->sim_bridge->register_hpd)
+			debug->sim_bridge->register_hpd(debug->sim_bridge,
+					dp_debug_sim_hpd_cb, debug);
+	}
 
 	dp_sim_update_port_num(debug->sim_bridge, 1);
 
-	if (debug->sim_bridge->register_hpd)
-		debug->sim_bridge->register_hpd(debug->sim_bridge,
-				dp_debug_sim_hpd_cb, debug);
-
 	return 0;
 }