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/ip_input.c b/net/ipv4/ip_input.c
index 3d4da2c..00bed6f 100644
--- a/net/ipv4/ip_input.c
+++ b/net/ipv4/ip_input.c
@@ -314,7 +314,7 @@
 	const struct iphdr *iph = ip_hdr(skb);
 	struct rtable *rt;
 
-	if (sysctl_ip_early_demux && !skb_dst(skb) && skb->sk == NULL) {
+	if (sysctl_ip_early_demux && !skb_dst(skb) && !skb->sk) {
 		const struct net_protocol *ipprot;
 		int protocol = iph->protocol;
 
@@ -387,7 +387,8 @@
 
 	IP_UPD_PO_STATS_BH(dev_net(dev), IPSTATS_MIB_IN, skb->len);
 
-	if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
+	skb = skb_share_check(skb, GFP_ATOMIC);
+	if (!skb) {
 		IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_INDISCARDS);
 		goto out;
 	}