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>
diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
index a2991bc..9f2cd47 100644
--- a/net/ipv4/ip_forward.c
+++ b/net/ipv4/ip_forward.c
@@ -111,8 +111,8 @@
 
 	skb->priority = rt_tos2priority(iph->tos);
 
-	return NF_HOOK(PF_INET, NF_INET_FORWARD, skb, skb->dev, rt->u.dst.dev,
-		       ip_forward_finish);
+	return NF_HOOK(NFPROTO_IPV4, NF_INET_FORWARD, skb, skb->dev,
+		       rt->u.dst.dev, ip_forward_finish);
 
 sr_failed:
 	/*