fs: Fix error checking for d_hash_and_lookup()

mainline inclusion
from mainline-v6.6-rc1
commit 0d5a4f8f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I8LNLY?from=project-issue

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=0d5a4f8f775ff990142cdc810a84eae078589d27



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

The d_hash_and_lookup() function returns error pointers or NULL.
Most incorrect error checks were fixed, but the one in int path_pts()
was forgotten.

Fixes: eedf265a ("devpts: Make each mount of devpts an independent filesystem.")
Signed-off-by: Wang Ming <machel@vivo.com>
Message-Id: <20230713120555.7025-1-machel@vivo.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Zizhi Wo <wozizhi@huawei.com>