mlxsw: spectrum: Fix compilation error when CLS_ACT isn't set

When CONFIG_NET_CLS_ACT isn't set 'struct tcf_exts' has no member named
'actions' and we therefore must not access it. Otherwise compilation
fails.

Fix this by introducing a new macro similar to tc_no_actions(), which
always returns 'false' if CONFIG_NET_CLS_ACT isn't set.

Fixes: 763b4b70 ("mlxsw: spectrum: Add support in matchall mirror TC offloading")
Reported-by: kbuild test robot <fengguang.wu@intel.com>
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>