CIFS: Fix memory leaks in SMB2_open

Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: Pavel Shilovsky <pshilovsky@samba.org>
Reviewed-by: Shirish Pargaonkar <spargaonkar@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>