batman-adv: use htons when possible

When comparing a network ordered value with a constant, it
is better to convert the constant at compile time by means
of htons() instead of converting the value at runtime using
ntohs().

This refactoring may slightly improve the code performance.

Moreover substitute __constant_htons() with htons() since
the latter increase readability and it is smart enough to be
as efficient as the former

Signed-off-by: Antonio Quartulli <ordex@autistici.org>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Acked-by: Simon Wunderlich <siwu@hrz.tu-chemnitz.de>
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 70da18a..5bb58d7 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -863,25 +863,25 @@
 	struct arphdr *arphdr;
 	uint8_t *hw_src, *hw_dst;
 	struct batadv_bla_claim_dst *bla_dst;
-	uint16_t proto;
+	__be16 proto;
 	int headlen;
 	unsigned short vid = BATADV_NO_FLAGS;
 	int ret;
 
 	ethhdr = eth_hdr(skb);
 
-	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
+	if (ethhdr->h_proto == htons(ETH_P_8021Q)) {
 		vhdr = (struct vlan_ethhdr *)ethhdr;
 		vid = ntohs(vhdr->h_vlan_TCI) & VLAN_VID_MASK;
 		vid |= BATADV_VLAN_HAS_TAG;
-		proto = ntohs(vhdr->h_vlan_encapsulated_proto);
+		proto = vhdr->h_vlan_encapsulated_proto;
 		headlen = sizeof(*vhdr);
 	} else {
-		proto = ntohs(ethhdr->h_proto);
+		proto = ethhdr->h_proto;
 		headlen = ETH_HLEN;
 	}
 
-	if (proto != ETH_P_ARP)
+	if (proto != htons(ETH_P_ARP))
 		return 0; /* not a claim frame */
 
 	/* this must be a ARP frame. check if it is a claim. */
@@ -1379,7 +1379,7 @@
 
 	ethhdr = (struct ethhdr *)(((uint8_t *)skb->data) + hdr_size);
 
-	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {
+	if (ethhdr->h_proto == htons(ETH_P_8021Q)) {
 		if (!pskb_may_pull(skb, hdr_size + VLAN_ETH_HLEN))
 			return 0;