ipv4: additional update of dev_net(dev) to struct *net in ip_fragment.c, NULL ptr OOPS

ipv4 ip_frag_reasm(), fully replace 'dev_net(dev)' with 'net', defined
previously patched into 2.6.29.

Between 2.6.28.10 and 2.6.29, net/ipv4/ip_fragment.c was patched,
changing from dev_net(dev) to container_of(...).  Unfortunately the goto
section (out_fail) on oversized packets inside ip_frag_reasm() didn't
get touched up as well.  Oversized IP packets cause a NULL pointer
dereference and immediate hang.

I discovered this running openvasd and my previous email on this is
titled:  NULL pointer dereference at 2.6.32-rc8:net/ipv4/ip_fragment.c:566
Signed-off-by: NDavid Ford <david@blue-labs.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/ip_fragment.c

@@ -563,7 +563,7 @@ static int ip_frag_reasm(struct ipq *qp, struct sk_buff *prev,
 		printk(KERN_INFO "Oversized IP packet from %pI4.\n",
 			&qp->saddr);
 out_fail:
-	IP_INC_STATS_BH(dev_net(dev), IPSTATS_MIB_REASMFAILS);
+	IP_INC_STATS_BH(net, IPSTATS_MIB_REASMFAILS);
 	return err;
 }