netfilter: ipv4: use NFPROTO values for NF_HOOK invocation

The semantic patch that was used:
// <smpl>
@@
@@
(NF_HOOK
|NF_HOOK_COND
|nf_hook
)(
-PF_INET,
+NFPROTO_IPV4,
 ...)
// </smpl>

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>

net/ipv4/xfrm4_input.c

@@ -60,7 +60,7 @@ int xfrm4_transport_finish(struct sk_buff *skb, int async)
 	iph->tot_len = htons(skb->len);
 	ip_send_check(iph);
 
-	NF_HOOK(PF_INET, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
+	NF_HOOK(NFPROTO_IPV4, NF_INET_PRE_ROUTING, skb, skb->dev, NULL,
 		xfrm4_rcv_encap_finish);
 	return 0;
 }