The DRM pipeline handling code uses the entity's pipe list head to check
whether the entity is already included in a pipeline. This method is a
bit fragile in the sense that it uses list_empty() on a list_head that
is a list member. Replace it by a simpler check for the entity pipe
pointer.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
                         * Remove the RPF from the pipe and the list of BRU
                         * inputs.
                         */
-                       WARN_ON(list_empty(&rpf->entity.list_pipe));
+                       WARN_ON(!rpf->entity.pipe);
                        rpf->entity.pipe = NULL;
-                       list_del_init(&rpf->entity.list_pipe);
+                       list_del(&rpf->entity.list_pipe);
                        pipe->inputs[i] = NULL;
 
                        bru->inputs[rpf->bru_input].rpf = NULL;
                        continue;
                }
 
-               if (list_empty(&rpf->entity.list_pipe)) {
+               if (!rpf->entity.pipe) {
                        rpf->entity.pipe = pipe;
                        list_add_tail(&rpf->entity.list_pipe, &pipe->entities);
                }
                                           VI6_DPR_NODE_UNUSED);
 
                        entity->pipe = NULL;
-                       list_del_init(&entity->list_pipe);
+                       list_del(&entity->list_pipe);
 
                        continue;
                }