policy: make steering ability evaluation uniform

Usteer imposes minimum intervals for steering actions in order to avoid
creating endless roam-kick loops due to the decentral aspect of usteer.

Make these basic limits to roamsteering usable across band-steering and
signal-based roam-steering.

Signed-off-by: David Bauer <mail@david-bauer.net>

band_steering.c

@@ -81,7 +81,8 @@ void usteer_band_steering_perform_steer(struct usteer_local_node *ln)
 	ln->band_steering_interval = 0;
 
 	list_for_each_entry(si, &ln->node.sta_info, node_list) {
-		if (si->connected != STA_CONNECTED)
+		/* Check if client is eligable to be steerd */
+		if (!usteer_policy_can_perform_roam(si))
 			continue;
 
 		/* Skip clients with insufficient SNR-state */