bootstd: Move the bootflow list into an alist

Use an alist for this data structure as it is somewhat simpler to
manage. This means that bootstd holds a simple list of bootflow structs
and can drop it at will, without chasing down lists.

Signed-off-by: Simon Glass <sjg@chromium.org>

cmd/bootdev.c

@@ -81,7 +81,7 @@ static int do_bootdev_info(struct cmd_tbl *cmdtp, int flag, int argc,
 
 	dev = priv->cur_bootdev;
 
-	/* Count the number of bootflows, including how many are valid*/
+	/* Count the number of bootflows, including how many are valid */
 	num_valid = 0;
 	for (ret = bootdev_first_bootflow(dev, &bflow), i = 0;
 	     !ret;