[TIPC]: Fix simple sparse warnings

Tried to run the new tipc stack through sparse.
Following patch fixes all cases where 0 was used
as replacement of NULL.
Use NULL to document this is a pointer and to silence sparse.

This brough sparse warning count down with 127 to 24 warnings.

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Per Liden <per.liden@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/tipc/subscr.c b/net/tipc/subscr.c
index 5ff38b9..3ec4e2b 100644
--- a/net/tipc/subscr.c
+++ b/net/tipc/subscr.c
@@ -381,7 +381,7 @@
 				   struct tipc_name_seq const *dest)
 {
 	struct subscriber *subscriber;
-	struct iovec msg_sect = {0, 0};
+	struct iovec msg_sect = {NULL, 0};
 	spinlock_t *subscriber_lock;
 
 	dbg("subscr_named_msg_event: orig = %x own = %x,\n",
@@ -413,13 +413,13 @@
 	tipc_createport(topsrv.user_ref,
 			(void *)(unsigned long)subscriber->ref,
 			importance,
-			0,
-			0,
+			NULL,
+			NULL,
 			subscr_conn_shutdown_event,
-			0,
-			0,
+			NULL,
+			NULL,
 			subscr_conn_msg_event,
-			0,
+			NULL,
 			&subscriber->port_ref);
 	if (subscriber->port_ref == 0) {
 		warn("Memory squeeze; failed to create subscription port\n");
@@ -461,22 +461,22 @@
 	INIT_LIST_HEAD(&topsrv.subscriber_list);
 
 	spin_lock_bh(&topsrv.lock);
-	res = tipc_attach(&topsrv.user_ref, 0, 0);
+	res = tipc_attach(&topsrv.user_ref, NULL, NULL);
 	if (res) {
 		spin_unlock_bh(&topsrv.lock);
 		return res;
 	}
 
  	res = tipc_createport(topsrv.user_ref,
- 			      0,
+ 			      NULL,
  			      TIPC_CRITICAL_IMPORTANCE,
- 			      0,
- 			      0,
- 			      0,
- 			      0,
+ 			      NULL,
+ 			      NULL,
+ 			      NULL,
+ 			      NULL,
  			      subscr_named_msg_event,
- 			      0,
- 			      0,
+ 			      NULL,
+ 			      NULL,
  			      &topsrv.setup_port);
  	if (res)
 		goto failed;