batman-adv: prefer kmalloc_array to kmalloc when possible

Reported by checkpatch with the following warning:
WARNING: Prefer kmalloc_array over kmalloc with multiply

Signed-off-by: Antonio Quartulli <antonio@meshcoding.com>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>

net/batman-adv/distributed-arp-table.c

@@ -537,7 +537,8 @@ batadv_dat_select_candidates(struct batadv_priv *bat_priv, __be32 ip_dst)
 	if (!bat_priv->orig_hash)
 		return NULL;
 
-	res = kmalloc(BATADV_DAT_CANDIDATES_NUM * sizeof(*res), GFP_ATOMIC);
+	res = kmalloc_array(BATADV_DAT_CANDIDATES_NUM, sizeof(*res),
+			    GFP_ATOMIC);
 	if (!res)
 		return NULL;