ksmbd: fix memleak in session setup

If client send session setup request with unknown NTLMSSP message type,
session that does not included channel can be created. It will cause
session memleak. because ksmbd_sessions_deregister() does not destroy
session if channel is not included. This patch return error response if
client send the request unknown NTLMSSP message type.

Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-20593
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>