batman-adv: Don't do pointer arithmetic with void*

The size of void is currently set by gcc to 1, but is not well defined
in general. Therefore it is more advisable to cast it to char* before
doing pointer arithmetic.
Signed-off-by: Sven Eckelmann <sven@narfation.org>

net/batman-adv/originator.c

@@ -559,7 +559,7 @@ static int orig_node_del_if(struct orig_node *orig_node,
 	memcpy(data_ptr, orig_node->bcast_own, del_if_num * chunk_size);
 
 	/* copy second part */
-	memcpy(data_ptr + del_if_num * chunk_size,
+	memcpy((char *)data_ptr + del_if_num * chunk_size,
 	       orig_node->bcast_own + ((del_if_num + 1) * chunk_size),
 	       (max_if_num - del_if_num) * chunk_size);
 
@@ -579,7 +579,7 @@ static int orig_node_del_if(struct orig_node *orig_node,
 	memcpy(data_ptr, orig_node->bcast_own_sum,
 	       del_if_num * sizeof(uint8_t));
 
-	memcpy(data_ptr + del_if_num * sizeof(uint8_t),
+	memcpy((char *)data_ptr + del_if_num * sizeof(uint8_t),
 	       orig_node->bcast_own_sum + ((del_if_num + 1) * sizeof(uint8_t)),
 	       (max_if_num - del_if_num) * sizeof(uint8_t));