l2tp: cleanup kzalloc calls

Passing "sizeof(struct blah)" in kzalloc calls is less readable,
potentially prone to future bugs if the type of the pointer is changed,
and triggers checkpatch warnings.

Tweak the kzalloc calls in l2tp which use this form to avoid the
warning.
Signed-off-by: Tom Parkin <tparkin@katalix.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/l2tp/l2tp_core.c

@@ -1410,7 +1410,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
 	if (cfg)
 		encap = cfg->encap;
 
-	tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
+	tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
 	if (!tunnel) {
 		err = -ENOMEM;
 		goto err;
@@ -1647,7 +1647,7 @@ struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunn
 {
 	struct l2tp_session *session;
 
-	session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
+	session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL);
 	if (session) {
 		session->magic = L2TP_SESSION_MAGIC;
 		session->tunnel = tunnel;