bootstd: Add support for bootflows

Add support for bootflows, including maintaining a list of them and
iterating to find them.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/boot/bootstd-uclass.c b/boot/bootstd-uclass.c
index 4c71c28..266bd7c 100644
--- a/boot/bootstd-uclass.c
+++ b/boot/bootstd-uclass.c
@@ -45,7 +45,7 @@
 
 		bflow = list_first_entry(&priv->glob_head, struct bootflow,
 					 glob_node);
-		/* add later bootflow_remove(bflow); */
+		bootflow_remove(bflow);
 	}
 }