stm32f4: add serial print port

Add the stm32F4 board's serial ports support.
User can use it easily.
The user only need to edit the number of the usart.
The patch also fix the serial print out.

Last, this version of patch fix the first patch checkpatch.pl error.
Thanks to Kamil Lulko.

Signed-off-by: kunhuahuang <huangkunhua@gmail.com>
diff --git a/board/st/stm32f429-discovery/stm32f429-discovery.c b/board/st/stm32f429-discovery/stm32f429-discovery.c
index 2c4830f..2dd5d93 100644
--- a/board/st/stm32f429-discovery/stm32f429-discovery.c
+++ b/board/st/stm32f429-discovery/stm32f429-discovery.c
@@ -33,21 +33,21 @@
 	.otype = STM32_GPIO_OTYPE_PP,
 	.speed = STM32_GPIO_SPEED_50M,
 	.pupd = STM32_GPIO_PUPD_UP,
-	.af = STM32_GPIO_AF7
+	.af = STM32_GPIO_USART
 };
 
-static const struct stm32_gpio_dsc usart1_gpio[] = {
-	{STM32_GPIO_PORT_A, STM32_GPIO_PIN_9},	/* TX */
-	{STM32_GPIO_PORT_A, STM32_GPIO_PIN_10},	/* RX */
+static const struct stm32_gpio_dsc usart_gpio[] = {
+	{STM32_GPIO_PORT_X, STM32_GPIO_PIN_TX},	/* TX */
+	{STM32_GPIO_PORT_X, STM32_GPIO_PIN_RX},	/* RX */
 };
 
-int uart1_setup_gpio(void)
+int uart_setup_gpio(void)
 {
 	int i;
 	int rv = 0;
 
-	for (i = 0; i < ARRAY_SIZE(usart1_gpio); i++) {
-		rv = stm32_gpio_config(&usart1_gpio[i], &gpio_ctl_usart);
+	for (i = 0; i < ARRAY_SIZE(usart_gpio); i++) {
+		rv = stm32_gpio_config(&usart_gpio[i], &gpio_ctl_usart);
 		if (rv)
 			goto out;
 	}
@@ -272,7 +272,7 @@
 {
 	int res;
 
-	res = uart1_setup_gpio();
+	res = uart_setup_gpio();
 	if (res)
 		return res;