remove warning of ivisurface reassign on the ivilayer

The warning of ivisurface reassign can be removed. It is ok to reassign
a surface to a layer it is already on.

The warning started to show up during normal operations since patch
"hmi-controller: remove duplicate commit_changes in random mode".

Signed-off-by: Wataru Natsume <WATARU_NATSUME@xddp.denso.co.jp>
[Pekka: rewrote commit message, removed unneeded comments.]
Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>

ivi-shell/ivi-layout.c

@@ -2417,10 +2417,8 @@ ivi_layout_layer_add_surface(struct ivi_layout_layer *ivilayer,
 		return IVI_FAILED;
 	}
 
-	if (addsurf->on_layer == ivilayer) {
-		weston_log("ivi_layout_layer_add_surface: addsurf is already available\n");
+	if (addsurf->on_layer == ivilayer)
 		return IVI_SUCCEEDED;
-	}
 
 	wl_list_for_each_safe(ivisurf, next, &layout->surface_list, link) {
 		if (ivisurf->id_surface == addsurf->id_surface) {