scoutfs: return errors from read_items

The introduction of the helper to handle stale segment retrying was
masking errors.  It's meant to pass through the caller's return status
when it doesn't return -EAGAIN to trigger stale read retries.

Signed-off-by: Zach Brown <zab@versity.com>

kmod/src/manifest.c

@@ -490,7 +490,7 @@ static int handle_stale_btree(struct super_block *sb,
 		return -EIO;
 	}
 
-	return 0;
+	return ret;
 }
 
 static int cmp_ment_ref_segno(void *priv, struct list_head *A,