ipv4: coding style: comparison for equality with NULL

The ipv4 code uses a mixture of coding styles. In some instances check
for NULL pointer is done as x == NULL and sometimes as !x. !x is
preferred according to checkpatch and this patch makes the code
consistent by adopting the latter form.

No changes detected by objdiff.

Signed-off-by: Ian Morris <ipm@chirality.org.uk>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/raw.c

@@ -363,7 +363,7 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
 	skb = sock_alloc_send_skb(sk,
 				  length + hlen + tlen + 15,
 				  flags & MSG_DONTWAIT, &err);
-	if (skb == NULL)
+	if (!skb)
 		goto error;
 	skb_reserve(skb, hlen);