netfilter: queue: use NFPROTO_ for queue callsites

af is an nfproto.

Signed-off-by: Jan Engelhardt <jengelh@medozas.de>
diff --git a/net/netfilter/nf_queue.c b/net/netfilter/nf_queue.c
index 4f2310c..3a6fd77 100644
--- a/net/netfilter/nf_queue.c
+++ b/net/netfilter/nf_queue.c
@@ -204,10 +204,10 @@
 				  queuenum);
 
 	switch (pf) {
-	case AF_INET:
+	case NFPROTO_IPV4:
 		skb->protocol = htons(ETH_P_IP);
 		break;
-	case AF_INET6:
+	case NFPROTO_IPV6:
 		skb->protocol = htons(ETH_P_IPV6);
 		break;
 	}