fixed rx_buffer[] initialization for rt_serial_init()

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@514 bbd45198-f89e-11dd-88c7-29a3b14d5316

libcpu/arm/s3c24x0/serial.c

@@ -37,7 +37,7 @@ static rt_err_t rt_serial_init (rt_device_t dev)
 		{
 			rt_memset(uart->int_rx->rx_buffer, 0, 
 				sizeof(uart->int_rx->rx_buffer));
-			uart->int_rx->read_index = uart->int_rx->read_index = 0;
+			uart->int_rx->read_index = uart->int_rx->save_index = 0;
 		}
 		
 		if (dev->flag & RT_DEVICE_FLAG_INT_TX)