When destroying the instance, destroy the head rhashtable.
Fixes: 05cd271fd61a ("cls_flower: Support multiple masks per priority") Reported-by: Vlad Buslov <vladbu@mellanox.com> Reviewed-by: Roi Dayan <roid@mellanox.com> Reviewed-by: Jiri Pirko <jiri@mellanox.com> Signed-off-by: Paul Blakey <paulb@mellanox.com> Reviewed-by: Simon Horman <simon.horman@netronome.com> Signed-off-by: David S. Miller <davem@davemloft.net>