[CIFS] NTLMv2 support part 5

NTLMv2 authentication (stronger authentication than default NTLM) which
many servers support now works.  There was a problem with the construction
of the security blob in the older code.  Currently requires
	/proc/fs/cifs/Experimental to be set to 2
and
	/proc/fs/cifs/SecurityFlags to be set to 0x4004 (to require using
	NTLMv2 instead of default of NTLM)

Next we will check signing to make sure optional NTLMv2 packet signing also
works.

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