IB/mlx4: Use list_for_each_entry_safe

Simplify the code in search_relocate_mgid0_group with by using
list_for_each_entry_safe().
Signed-off-by: Geliang Tang <geliangtang@163.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/hw/mlx4/mcg.c

@@ -747,14 +747,11 @@ static struct mcast_group *search_relocate_mgid0_group(struct mlx4_ib_demux_ctx
 						       __be64 tid,
 						       union ib_gid *new_mgid)
 {
-	struct mcast_group *group = NULL, *cur_group;
+	struct mcast_group *group = NULL, *cur_group, *n;
 	struct mcast_req *req;
-	struct list_head *pos;
-	struct list_head *n;
 
 	mutex_lock(&ctx->mcg_table_lock);
-	list_for_each_safe(pos, n, &ctx->mcg_mgid0_list) {
-		group = list_entry(pos, struct mcast_group, mgid0_list);
+	list_for_each_entry_safe(group, n, &ctx->mcg_mgid0_list, mgid0_list) {
 		mutex_lock(&group->lock);
 		if (group->last_req_tid == tid) {
 			if (memcmp(new_mgid, &mgid0, sizeof mgid0)) {