[bsp][stm32f429-apollo] Change the SDIO initialization frequency to 400K for improve reliability.

bsp/stm32f429-apollo/drivers/drv_sdio_sd.c

@@ -21,7 +21,7 @@ rt_uint8_t SD_Init(void)
     SDCARD_Handler.Init.ClockPowerSave=SDIO_CLOCK_POWER_SAVE_DISABLE;    //空闲时不关闭时钟电源
     SDCARD_Handler.Init.BusWide=SDIO_BUS_WIDE_1B;                        //1位数据线
     SDCARD_Handler.Init.HardwareFlowControl=SDIO_HARDWARE_FLOW_CONTROL_DISABLE;//关闭硬件流控
-    SDCARD_Handler.Init.ClockDiv=SDIO_TRANSFER_CLK_DIV;            //SD传输时钟频率最大25MHZ
+    SDCARD_Handler.Init.ClockDiv=SDIO_INIT_CLK_DIV;                 //初始化时钟为400KHZ
     
     SD_Error=HAL_SD_Init(&SDCARD_Handler,&SDCardInfo);
     if(SD_Error!=SD_OK) return 1;