mlxsw: spectrum_acl: Remove failed_rollback dead end

Currently if a rollback ends with error, the vregion is in a zombie
state until end of the existence. Instead of that, rather try to
continue where rollback ended later on (after rehash interval).

Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>