Do not send ClientGUID on SMB2.02 dialect

ClientGUID must be zero for SMB2.02 dialect.  See section 2.2.3
of MS-SMB2. For SMB2.1 and later it must be non-zero.

Signed-off-by: Steve French <smfrench@gmail.com>
CC: Sachin Prabhu <sprabhu@redhat.com>