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: 763b4b70af ("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>

include/net/act_api.h

@@ -192,6 +192,9 @@ int tcf_action_copy_stats(struct sk_buff *, struct tc_action *, int);
 #define tc_for_each_action(_a, _exts) \
 	list_for_each_entry(a, &(_exts)->actions, list)
 
+#define tc_single_action(_exts) \
+	(list_is_singular(&(_exts)->actions))
+
 static inline void tcf_action_stats_update(struct tc_action *a, u64 bytes,
 					   u64 packets, u64 lastuse)
 {
@@ -205,6 +208,7 @@ static inline void tcf_action_stats_update(struct tc_action *a, u64 bytes,
 
 #define tc_no_actions(_exts) true
 #define tc_for_each_action(_a, _exts) while ((void)(_a), 0)
+#define tc_single_action(_exts) false
 #define tcf_action_stats_update(a, bytes, packets, lastuse)
 
 #endif /* CONFIG_NET_CLS_ACT */