WPS: Remove unused struct subscr_addr parent pointer

src/wps/wps_upnp.c

@@ -377,7 +377,6 @@ static void subscr_addr_add_url(struct subscription *s, const char *url)
 		a = os_zalloc(sizeof(*a) + alloc_len);
 		if (a == NULL)
 			continue;
-		a->s = s;
 		mem = (void *) (a + 1);
 		a->domain_and_port = mem;
 		strcpy(mem, domain_and_port);

src/wps/wps_upnp_i.h

@@ -68,7 +68,6 @@ struct advertisement_state_machine {
  */
 struct subscr_addr {
 	struct dl_list list;
-	struct subscription *s; /* parent */
 	char *domain_and_port; /* domain and port part of url */
 	char *path; /* "filepath" part of url (from "mem") */
 	struct sockaddr_in saddr; /* address for doing connect */