staging: greybus: es2: fix arpc request size

Fix size field of arpc message request by using the header size and not
the pointer size.
Signed-off-by: Rui Miguel Silva <rmfrfs@gmail.com>
Reviewed-by: Viresh Kumar <viresh.kumar@linaro.org>
Reviewed-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/greybus/es2.c

@@ -1033,7 +1033,7 @@ static struct arpc *arpc_alloc(void *payload, u16 size, u8 type)
 		goto err_free_req;
 
 	rpc->req->type = type;
-	rpc->req->size = cpu_to_le16(sizeof(rpc->req) + size);
+	rpc->req->size = cpu_to_le16(sizeof(*rpc->req) + size);
 	memcpy(rpc->req->data, payload, size);
 
 	init_completion(&rpc->response_received);