drm/amd/display: Emulate Display Hotplug Hang

[WHY]
Driver reports 0 display when the virtual display is still present, and
causes P-state hang in FW.

[HOW]
When enumerating through streams, check for active planes and use that
to indicate number of displays.
Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: Daniel Sa <Daniel.Sa@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/dc/clk_mgr/clk_mgr.c

@@ -59,6 +59,7 @@ int clk_mgr_helper_get_active_display_cnt(
 	display_count = 0;
 	for (i = 0; i < context->stream_count; i++) {
 		const struct dc_stream_state *stream = context->streams[i];
+		const struct dc_stream_status *stream_status = &context->stream_status[i];
 
 		/* Don't count SubVP phantom pipes as part of active
 		 * display count
@@ -66,13 +67,7 @@ int clk_mgr_helper_get_active_display_cnt(
 		if (dc_state_get_stream_subvp_type(context, stream) == SUBVP_PHANTOM)
 			continue;
 
-		/*
-		 * Only notify active stream or virtual stream.
-		 * Need to notify virtual stream to work around
-		 * headless case. HPD does not fire when system is in
-		 * S0i2.
-		 */
-		if (!stream->dpms_off || stream->signal == SIGNAL_TYPE_VIRTUAL)
+		if (!stream->dpms_off || (stream_status && stream_status->plane_count))
 			display_count++;
 	}