MMFMWK-8006 waylandsink: don't check if buffer used by compositor when attach

when sink do resize, sink will attach last buffer again.

upstream status: Pending
https://bugzilla.gnome.org/show_bug.cgi?id=796326
diff --git a/ext/wayland/wlbuffer.c b/ext/wayland/wlbuffer.c
index 4ac99ef..c196230 100644
--- a/ext/wayland/wlbuffer.c
+++ b/ext/wayland/wlbuffer.c
@@ -220,8 +220,6 @@
 void
 gst_wl_buffer_attach (GstWlBuffer * self, struct wl_surface *surface)
 {
-  g_return_if_fail (self->used_by_compositor == FALSE);
-
   wl_surface_attach (surface, self->wlbuffer, 0, 0);
 
   /* Add a reference to the buffer. This represents the fact that