mlxsw: spectrum_acl: Use block variable in mlxsw_sp_acl_rule_del()

On couple of places in mlxsw_sp_acl_rule_del(), block variable is not
used directly as it could be. So do it.

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>