net/sched: actions: remove unused 'order'

after commit 4097e9d2 ("net: sched: don't use tc_action->order during
action dump"), 'act->order' is initialized but then it's no more read, so
we can just remove this member of struct tc_action.

CC: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: Davide Caratti <dcaratti@redhat.com>
Acked-by: Jiri Pirko <jiri@mellanox.com>
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>