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>
diff --git a/net/batman-adv/hash.c b/net/batman-adv/hash.c
index 63bdf7e..7c1c630 100644
--- a/net/batman-adv/hash.c
+++ b/net/batman-adv/hash.c
@@ -46,12 +46,12 @@
 	if (!hash)
 		return NULL;
 
-	hash->table = kmalloc(sizeof(*hash->table) * size, GFP_ATOMIC);
+	hash->table = kmalloc_array(size, sizeof(*hash->table), GFP_ATOMIC);
 	if (!hash->table)
 		goto free_hash;
 
-	hash->list_locks = kmalloc(sizeof(*hash->list_locks) * size,
-				   GFP_ATOMIC);
+	hash->list_locks = kmalloc_array(size, sizeof(*hash->list_locks),
+					 GFP_ATOMIC);
 	if (!hash->list_locks)
 		goto free_table;