batman-adv: use the const qualifier in hash functions

The data argument in each hash function should carry the
"const" qualifier as it is never modified.

Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
diff --git a/net/batman-adv/bridge_loop_avoidance.c b/net/batman-adv/bridge_loop_avoidance.c
index 724adf0..5e834c1 100644
--- a/net/batman-adv/bridge_loop_avoidance.c
+++ b/net/batman-adv/bridge_loop_avoidance.c
@@ -57,7 +57,7 @@
 static inline uint32_t batadv_choose_backbone_gw(const void *data,
 						 uint32_t size)
 {
-	struct batadv_claim *claim = (struct batadv_claim *)data;
+	const struct batadv_claim *claim = (struct batadv_claim *)data;
 	uint32_t hash = 0;
 
 	hash = batadv_hash_bytes(hash, &claim->addr, sizeof(claim->addr));