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>
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 294af16..9f525a2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -633,7 +633,7 @@
 
 	sk = __udp4_lib_lookup(net, iph->daddr, uh->dest,
 			iph->saddr, uh->source, skb->dev->ifindex, udptable);
-	if (sk == NULL) {
+	if (!sk) {
 		ICMP_INC_STATS_BH(net, ICMP_MIB_INERRORS);
 		return;	/* No socket for error */
 	}
@@ -1011,7 +1011,7 @@
 	if (connected)
 		rt = (struct rtable *)sk_dst_check(sk, 0);
 
-	if (rt == NULL) {
+	if (!rt) {
 		struct net *net = sock_net(sk);
 
 		fl4 = &fl4_stack;
@@ -1619,7 +1619,7 @@
 
 	for (i = 0; i < count; i++) {
 		sk = stack[i];
-		if (likely(skb1 == NULL))
+		if (likely(!skb1))
 			skb1 = (i == final) ? skb : skb_clone(skb, GFP_ATOMIC);
 
 		if (!skb1) {