fix some bugs with sd spi (#320)

* change sd init speed
* add pullup on bus

firmware/targets/f4/Src/spi.c

@@ -156,21 +156,21 @@ void HAL_SPI_MspInit(SPI_HandleTypeDef* spiHandle)
   // SD Card need faster spi gpio
   GPIO_InitStruct.Pin = GPIO_PIN_2;
   GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
-  GPIO_InitStruct.Pull = GPIO_NOPULL;
+  GPIO_InitStruct.Pull = GPIO_PULLUP;
   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
   GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
   HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
 
   GPIO_InitStruct.Pin = SPI_D_MOSI_Pin;
   GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
-  GPIO_InitStruct.Pull = GPIO_NOPULL;
+  GPIO_InitStruct.Pull = GPIO_PULLUP;
   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
   GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
   HAL_GPIO_Init(SPI_D_MOSI_GPIO_Port, &GPIO_InitStruct);
 
   GPIO_InitStruct.Pin = SPI_D_SCK_Pin;
   GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
-  GPIO_InitStruct.Pull = GPIO_NOPULL;
+  GPIO_InitStruct.Pull = GPIO_PULLUP;
   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
   GPIO_InitStruct.Alternate = GPIO_AF5_SPI2;
   HAL_GPIO_Init(SPI_D_SCK_GPIO_Port, &GPIO_InitStruct);

firmware/targets/f4/api-hal/api-hal-spi-config.c

@@ -37,7 +37,7 @@ const SPIDevice sd_slow_spi = {
         .CLKPolarity = SPI_POLARITY_LOW,
         .CLKPhase = SPI_PHASE_1EDGE,
         .NSS = SPI_NSS_SOFT,
-        .BaudRatePrescaler = SPI_BAUDRATEPRESCALER_256,
+        .BaudRatePrescaler = SPI_BAUDRATEPRESCALER_32,
         .FirstBit = SPI_FIRSTBIT_MSB,
         .TIMode = SPI_TIMODE_DISABLE,
         .CRCCalculation = SPI_CRCCALCULATION_DISABLE,