OMAPFB: remove manager->device references

With the introduction of output entities, managers will now connect to outputs.
Use the helper op for overlays named get_device. This will abstract away the
information on how to get the device from an overlay.

Using the helper function will reduce the number of pointer dereferences a user
of OMAPDSS needs to do and reduce risk of a NULL dereference.

Signed-off-by: Archit Taneja <archit@ti.com>
diff --git a/drivers/video/omap2/omapfb/omapfb.h b/drivers/video/omap2/omapfb/omapfb.h
index 30361a0..5ced9b3 100644
--- a/drivers/video/omap2/omapfb/omapfb.h
+++ b/drivers/video/omap2/omapfb/omapfb.h
@@ -148,8 +148,9 @@
 
 	/* XXX: returns the display connected to first attached overlay */
 	for (i = 0; i < ofbi->num_overlays; i++) {
-		if (ofbi->overlays[i]->manager)
-			return ofbi->overlays[i]->manager->device;
+		struct omap_overlay *ovl = ofbi->overlays[i];
+
+		return ovl->get_device(ovl);
 	}
 
 	return NULL;