ksmbd: use proper errno instead of -1 in smb2_get_ksmbd_tcon()

mainline inclusion
from mainline-5.15-rc1
commit c6ce2b57
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I60T7G
CVE: NA

Reference: https://git.kernel.org/torvalds/linux/c/c6ce2b5716b0



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Use proper errno instead of -1 in smb2_get_ksmbd_tcon().

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>