[HUST CSE] Fix nullptr issue in bsp/rv32m1_vega/ri5cy/board/fsl_host.c (#7236)

During the process of statically checking the source code, it was found that this judgment directly obtained the member of the structure pointer without performing a null pointer check. When an upstream function has an exception and passes in a null pointer, a runtime error will occur.

bsp/rv32m1_vega/ri5cy/board/fsl_host.c

@@ -51,7 +51,7 @@ static status_t USDHC_TransferFunction(USDHC_Type *base, usdhc_transfer_t *conte
 
     usdhc_adma_config_t dmaConfig;
 
-    if (content->data != NULL)
+    if (content != NULL && content->data != NULL)
     {
         memset(&dmaConfig, 0, sizeof(usdhc_adma_config_t));
         /* config adma */