OMAPDSS: modify get/find functions to go through the device chain

In the future will have arbitrarily long video pipeline chains, instead
of the current two-entities-per-pipeline model.

This patch changes the affected get/find style functions so that they
properly go through the video pipeline chain, for example when getting
the overlay manager connected to a given display.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/omap2/dss/apply.c

@@ -422,7 +422,19 @@ static void wait_pending_extra_info_updates(void)
 
 static struct omap_dss_device *dss_mgr_get_device(struct omap_overlay_manager *mgr)
 {
-	return mgr->output ? mgr->output->device : NULL;
+	struct omap_dss_device *dssdev;
+
+	dssdev = mgr->output;
+	if (dssdev == NULL)
+		return NULL;
+
+	while (dssdev->device)
+		dssdev = dssdev->device;
+
+	if (dssdev->driver)
+		return dssdev;
+	else
+		return NULL;
 }
 
 static struct omap_dss_device *dss_ovl_get_device(struct omap_overlay *ovl)

drivers/video/omap2/dss/output.c

@@ -146,7 +146,13 @@ EXPORT_SYMBOL(omap_dss_find_output_by_node);
 
 struct omap_dss_device *omapdss_find_output_from_display(struct omap_dss_device *dssdev)
 {
-	return omap_dss_get_device(dssdev->output);
+	while (dssdev->output)
+		dssdev = dssdev->output;
+
+	if (dssdev->id != 0)
+		return omap_dss_get_device(dssdev);
+
+	return NULL;
 }
 EXPORT_SYMBOL(omapdss_find_output_from_display);