batman-adv: improve DAT documentation

Add missing documentation for BATADV_DAT_ADDR_MAX and
convert an existing documentation to kerneldoc

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

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

@@ -25,6 +25,9 @@
 
 #include <linux/if_arp.h>
 
+/**
+ * BATADV_DAT_ADDR_MAX - maximum address value in the DHT space
+ */
 #define BATADV_DAT_ADDR_MAX ((batadv_dat_addr_t)~(batadv_dat_addr_t)0)
 
 void batadv_dat_status_update(struct net_device *net_dev);

net/batman-adv/types.h

@@ -24,8 +24,9 @@
 
 #ifdef CONFIG_BATMAN_ADV_DAT
 
-/* batadv_dat_addr_t is the type used for all DHT addresses. If it is changed,
- * BATADV_DAT_ADDR_MAX is changed as well.
+/**
+ * batadv_dat_addr_t - it is the type used for all DHT addresses. If it is
+ *  changed, BATADV_DAT_ADDR_MAX is changed as well.
  *
  * *Please be careful: batadv_dat_addr_t must be UNSIGNED*
  */