[I2C] Fix HAL F4

In function:
static HAL_StatusTypeDef I2C_Master_SB(I2C_HandleTypeDef *hi2c)

This check has been added:
      if ((hi2c->hdmatx->XferCpltCallback != NULL) || (hi2c->hdmarx->XferCpltCallback != NULL))
      {
        /* Enable DMA Request */
        SET_BIT(hi2c->Instance->CR2, I2C_CR2_DMAEN);
      }

But, in case of the DMA is not used, hi2c->hdmatx and hi2c->hdmarx are NULL.
In this case, hi2c->hdma(rx|tx)->XferCpltCallback can be not NULL
then I2C_CR2_DMAEN is set while it should not.
As this bit is checked several time to know if DMA is used or not this
raised an exception handler.

Fix #463

Signed-off-by: Frederic.Pillon <[email protected]>

Author: fpistm

system/Drivers/STM32F4xx_HAL_Driver/Src/stm32f4xx_hal_i2c.c

@@ -5449,7 +5449,8 @@ static void I2C_Master_SB(I2C_HandleTypeDef *hi2c)
         hi2c->Instance->DR = I2C_7BIT_ADD_READ(hi2c->Devaddress);
       }
 
-      if ((hi2c->hdmatx->XferCpltCallback != NULL) || (hi2c->hdmarx->XferCpltCallback != NULL))
+      if (((hi2c->hdmatx) && (hi2c->hdmatx->XferCpltCallback != NULL)) ||
+          ((hi2c->hdmarx) && (hi2c->hdmarx->XferCpltCallback != NULL)))
       {
         /* Enable DMA Request */
         SET_BIT(hi2c->Instance->CR2, I2C_CR2_DMAEN);