CIFS: Fix maximum SMB2 header size

Currently the maximum size of SMB2/3 header is set incorrectly which
leads to hanging of directory listing operations on encrypted SMB3
connections. Fix this by setting the maximum size to 170 bytes that
is calculated as RFC1002 length field size (4) + transform header
size (52) + SMB2 header size (64) + create response size (56).

Cc: <stable@vger.kernel.org>
Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Acked-by: Sachin Prabhu <sprabhu@redhat.com>