batman-adv: Remove dangling declaration of hash_remove_element

Signed-off-by: Sven Eckelmann <sven@narfation.org>

net/batman-adv/hash.h

@@ -49,11 +49,6 @@ struct hashtable_t {
 /* allocates and clears the hash */
 struct hashtable_t *hash_new(int size);
 
-/* remove element if you already found the element you want to delete and don't
- * need the overhead to find it again with hash_remove().  But usually, you
- * don't want to use this function, as it fiddles with hash-internals. */
-void *hash_remove_element(struct hashtable_t *hash, struct element_t *elem);
-
 /* free only the hashtable and the hash itself. */
 void hash_destroy(struct hashtable_t *hash);