Revert "wireless: do not enable 'isolate' if 'multicast_to_unicast' is not defined"

This reverts commit 3f4dc703.

scripts/netifd-wireless.sh

@@ -297,7 +297,6 @@ _wireless_set_brsnoop_isolation() {
 	json_get_var isolate isolate
 
 	[ ${isolate:-0} -gt 0 -o -z "$network_bridge" ] && return
-	[ -z "$multicast_to_unicast" ] && return
 	[ ${multicast_to_unicast:-1} -gt 0 ] && json_add_boolean isolate 1
 }