[CIFS] Remove older session setup implementation

Two years ago, when the session setup code in cifs was rewritten and moved
to fs/cifs/sess.c, we were asked to keep the old code for a release or so
(which could be reenabled at runtime) since it was such a large change and
because the asn (SPNEGO) and NTLMSSP code was not rewritten and needed to
be. This was useful to avoid regressions, but is long overdue to be removed.
Now that the Kerberos (asn/spnego) code is working in fs/cifs/sess.c,
and the NTLMSSP code moved (NTLMSSP blob setup be rewritten with the
next patch in this series) quite a bit of dead code from fs/cifs/connect.c
now can be removed.

This old code should have been removed last year, but the earlier krb5
patches did not move/remove the NTLMSSP code which we had asked to
be done first.  Since no one else volunteered, I am doing it now.

It is extremely important that we continue to examine the documentation
for this area, to make sure our code continues to be uptodate with
changes since Windows 2003.

Signed-off-by: Steve French <sfrench@us.ibm.com>