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

Need this check but change to return directly instead of assert fail

This reverts commit 61a132df0ddb90a9ebef1ae6ec4df4d98eb1712f.
diff --git a/ext/wayland/wlbuffer.c b/ext/wayland/wlbuffer.c
index c196230..4ac99ef 100644
--- a/ext/wayland/wlbuffer.c
+++ b/ext/wayland/wlbuffer.c
@@ -220,6 +220,8 @@
 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