batman-adv: use eth_hdr() when it makes sense

Instead of casting the result of skb_mac_header() to
"struct ethhdr *" every time, the eth_hdr inline function
can be use to beautify the code and improve its readability.

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
diff --git a/net/batman-adv/network-coding.c b/net/batman-adv/network-coding.c
index e84629e..0787a34 100644
--- a/net/batman-adv/network-coding.c
+++ b/net/batman-adv/network-coding.c
@@ -1245,7 +1245,7 @@
 		return;
 
 	/* Set the mac header as if we actually sent the packet uncoded */
-	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	ethhdr = eth_hdr(skb);
 	memcpy(ethhdr->h_source, ethhdr->h_dest, ETH_ALEN);
 	memcpy(ethhdr->h_dest, eth_dst_new, ETH_ALEN);
 
@@ -1423,7 +1423,7 @@
 {
 	struct batadv_unicast_packet *packet;
 	struct batadv_nc_path *nc_path;
-	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	struct ethhdr *ethhdr = eth_hdr(skb);
 	__be32 packet_id;
 	u8 *payload;
 
@@ -1482,7 +1482,7 @@
 void batadv_nc_skb_store_sniffed_unicast(struct batadv_priv *bat_priv,
 					 struct sk_buff *skb)
 {
-	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	struct ethhdr *ethhdr = eth_hdr(skb);
 
 	if (batadv_is_my_mac(bat_priv, ethhdr->h_dest))
 		return;
@@ -1533,7 +1533,7 @@
 	skb_reset_network_header(skb);
 
 	/* Reconstruct original mac header */
-	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	ethhdr = eth_hdr(skb);
 	memcpy(ethhdr, &ethhdr_tmp, sizeof(*ethhdr));
 
 	/* Select the correct unicast header information based on the location
@@ -1677,7 +1677,7 @@
 		return NET_RX_DROP;
 
 	coded_packet = (struct batadv_coded_packet *)skb->data;
-	ethhdr = (struct ethhdr *)skb_mac_header(skb);
+	ethhdr = eth_hdr(skb);
 
 	/* Verify frame is destined for us */
 	if (!batadv_is_my_mac(bat_priv, ethhdr->h_dest) &&