btrfs-progs: convert: Add missing return for HOLE mode when checking convert image

In check_convert_image(), for normal HOLE case, if the file extents are
smaller than image size, we set ret to -EINVAL and print error message.

But forget to return.

This patch adds the missing return to fix it.

Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
Signed-off-by: David Sterba <dsterba@suse.com>

convert/main.c

@@ -1559,6 +1559,7 @@ next:
 			ret = -EINVAL;
 			error("inode %llu has some file extents not checked",
 				ino);
+			return ret;
 		}
 	}