udf: refactor udf_next_aext() to handle error

Since udf_current_aext() has error handling, udf_next_aext() should have
error handling too. Besides, when too many indirect extents found in one
inode, return -EFSCORRUPTED; when reading block failed, return -EIO.

Signed-off-by: Zhao Mengmeng <zhaomengmeng@kylinos.cn>
Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://patch.msgid.link/20241001115425.266556-3-zhaomzhao@126.com