ivi-shell: add new method to remove a callback to get notificaiton of ivi_layer property changes.

To get property changes of ivi_layer, callbacks can be registered.
However there was no API to remove a callback rather than removing all
callbacks by using layer_remove_notification.
layer_remove_notification_by_callback can do it.

Signed-off-by: Nobuhiko Tanibata <NOBUHIKO_TANIBATA@xddp.denso.co.jp>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.co.uk>
diff --git a/ivi-shell/ivi-layout-export.h b/ivi-shell/ivi-layout-export.h
index ed8db9d..2f93811 100644
--- a/ivi-shell/ivi-layout-export.h
+++ b/ivi-shell/ivi-layout-export.h
@@ -790,6 +790,13 @@
 							surface_property_notification_func callback,
 							void *userdata);
 
+	/**
+	 * \brief remove notification by callback on property changes of ivi_layer
+	 */
+	void (*layer_remove_notification_by_callback)(struct ivi_layout_layer *ivilayer,
+						      layer_property_notification_func callback,
+						      void *userdata);
+
 };
 
 #ifdef __cplusplus