[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/cifs_spnego.c b/fs/cifs/cifs_spnego.c
index 2434ab0..117ef4b 100644
--- a/fs/cifs/cifs_spnego.c
+++ b/fs/cifs/cifs_spnego.c
@@ -114,9 +114,11 @@
 
 	dp = description + strlen(description);
 
-	/* for now, only sec=krb5 is valid */
+	/* for now, only sec=krb5 and sec=mskrb5 are valid */
 	if (server->secType == Kerberos)
 		sprintf(dp, ";sec=krb5");
+	else if (server->secType == MSKerberos)
+		sprintf(dp, ";sec=mskrb5");
 	else
 		goto out;