[MS-SMB] 2.2.4.5.2.1 states:

"ChallengeLength (1 byte): When the CAP_EXTENDED_SECURITY bit is set,
 the server MUST set this value to zero and clients MUST ignore this
 value."
Signed-off-by: Noel Power <noel.power@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>