Revert "configfs: fix a race in configfs_lookup()"

This reverts commit c709c7ca which is
commit c42dd069

 upstream.

It was backported incorrectly, and will come back later in a way that
actually works.

Cc: Sishuai Gong <sishuai@purdue.edu>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Kyle Zeng <zengyhkyle@gmail.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/27f978f3-11ca-6054-5160-ab66d4c918bc@roeck-us.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>