netfilter: ipv6: use NFPROTO values for NF_HOOK invocation

The semantic patch that was used:
// <smpl>
@@
@@
(NF_HOOK
|NF_HOOK_THRESH
|nf_hook
)(
-PF_INET6,
+NFPROTO_IPV6,
 ...)
// </smpl>

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index e28f920..2c01dc6 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -142,7 +142,7 @@
 	/* Must drop socket now because of tproxy. */
 	skb_orphan(skb);
 
-	return NF_HOOK(PF_INET6, NF_INET_PRE_ROUTING, skb, dev, NULL,
+	return NF_HOOK(NFPROTO_IPV6, NF_INET_PRE_ROUTING, skb, dev, NULL,
 		       ip6_rcv_finish);
 err:
 	IP6_INC_STATS_BH(net, idev, IPSTATS_MIB_INHDRERRORS);
@@ -235,7 +235,7 @@
 
 int ip6_input(struct sk_buff *skb)
 {
-	return NF_HOOK(PF_INET6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
+	return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN, skb, skb->dev, NULL,
 		       ip6_input_finish);
 }