CIFS: don't log STATUS_NOT_FOUND errors for DFS

cifs.ko makes DFS queries regardless of the type of the server and
non-DFS servers are common. This often results in superfluous logging of
non-critical errors.

Signed-off-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <smfrench@gmail.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>