[CIFS] Fix to problem with getattr caused by invalidate simplification patch

Fix to earlier "Simplify invalidate part (try #6)" patch
That patch caused problems with connectathon test 5.

Reviewed-by: Jeff Layton <jlayton@samba.org>
Signed-off-by: Pavel Shilovsky <piastry@etersoft.ru>
Signed-off-by: Steve French <sfrench@us.ibm.com>