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/mcast.c b/net/ipv6/mcast.c
index bcd9719..773b9d1 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -1479,7 +1479,7 @@
 
 	payload_len = skb->len;
 
-	err = NF_HOOK(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, skb->dev,
+	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL, skb->dev,
 		      dst_output);
 out:
 	if (!err) {
@@ -1847,7 +1847,7 @@
 		goto err_out;
 
 	skb_dst_set(skb, dst);
-	err = NF_HOOK(PF_INET6, NF_INET_LOCAL_OUT, skb, NULL, skb->dev,
+	err = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_OUT, skb, NULL, skb->dev,
 		      dst_output);
 out:
 	if (!err) {