configfs: return -ENAMETOOLONG earlier in configfs_lookup

mainline inclusion
from mainline-v5.15-rc1
commit 417b962ddeca2b70eb72d28c87541bdad4e234f8
category: bugfix
bugzilla: 187567, https://gitee.com/openeuler/kernel/issues/I5PK1G


CVE: NA

--------------------------------

Just like most other file systems: get the simple checks out of the
way first.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Zhang Yi <yi.zhang@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>