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_gre.c b/net/ipv4/ip_gre.c
index 1060ca0..5fd7064 100644
--- a/net/ipv4/ip_gre.c
+++ b/net/ipv4/ip_gre.c
@@ -182,7 +182,7 @@
 	t = ip_tunnel_lookup(itn, skb->dev->ifindex, tpi->flags,
 			     iph->daddr, iph->saddr, tpi->key);
 
-	if (t == NULL)
+	if (!t)
 		return PACKET_REJECT;
 
 	if (t->parms.iph.daddr == 0 ||
@@ -423,7 +423,7 @@
 			return -EADDRNOTAVAIL;
 		dev = rt->dst.dev;
 		ip_rt_put(rt);
-		if (__in_dev_get_rtnl(dev) == NULL)
+		if (!__in_dev_get_rtnl(dev))
 			return -EADDRNOTAVAIL;
 		t->mlink = dev->ifindex;
 		ip_mc_inc_group(__in_dev_get_rtnl(dev), t->parms.iph.daddr);