clear DMA1_FLAG_TC2 in usart3 initialization

git-svn-id: https://rt-thread.googlecode.com/svn/trunk@1821 bbd45198-f89e-11dd-88c7-29a3b14d5316

bsp/stm32f10x/usart.c

@@ -243,7 +243,7 @@ static void DMA_Configuration(void)
 	DMA_InitStructure.DMA_BufferSize = 0;
 	DMA_Init(UART3_TX_DMA, &DMA_InitStructure);
 	DMA_ITConfig(UART3_TX_DMA, DMA_IT_TC | DMA_IT_TE, ENABLE);
-	DMA_ClearFlag(DMA1_FLAG_TC5);
+	DMA_ClearFlag(DMA1_FLAG_TC2);
 #endif
 }