[CIFS] distinguish between Kerberos and MSKerberos in upcall

Properly handle MSKRB5 by passing sec=mskrb5 to the upcall so that the
spengo blob can be generated appropriately. Also, make
decode_negTokenInit prefer whichever mechanism is first in the list.

Needed for some NetApp servers, and possibly some older
versions of Windows which treat the two KRB5 mechanisms differently.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/cifsglob.h b/fs/cifs/cifsglob.h
index 7e1cf26..8dfd6f2 100644
--- a/fs/cifs/cifsglob.h
+++ b/fs/cifs/cifsglob.h
@@ -80,7 +80,8 @@
 	NTLMv2,			/* Legacy NTLM auth with NTLMv2 hash */
 	RawNTLMSSP,		/* NTLMSSP without SPNEGO */
 	NTLMSSP,		/* NTLMSSP via SPNEGO */
-	Kerberos		/* Kerberos via SPNEGO */
+	Kerberos,		/* Kerberos via SPNEGO */
+	MSKerberos,		/* MS Kerberos via SPNEGO */
 };
 
 enum protocolEnum {