ksmbd: fix missing error code in smb2_lock

mainline inclusion
from mainline-5.15-rc1
commit 6c99dfc4
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G
CVE: NA

Reference: https://git.kernel.org/torvalds/linux/c/6c99dfc4c5f6



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

Dan report a warning that is missing error code in smb2_lock
from static checker. This patch add error code to avoid static checker
warning.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Jason Yan <yanaijie@huawei.com>
Signed-off-by: Zhong Jinghua <zhongjinghua@huawei.com>