[SK_BUFF]: Introduce arp_hdr(), remove skb->nh.arph

Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
index ebe740f..0ee74b1 100644
--- a/net/bridge/br_netfilter.c
+++ b/net/bridge/br_netfilter.c
@@ -670,7 +670,7 @@
 		(*pskb)->nh.raw += VLAN_HLEN;
 	}
 
-	if (skb->nh.arph->ar_pln != 4) {
+	if (arp_hdr(skb)->ar_pln != 4) {
 		if (IS_VLAN_ARP(skb)) {
 			skb_push(*pskb, VLAN_HLEN);
 			(*pskb)->nh.raw -= VLAN_HLEN;