example/sdspi: fix incorrect SPI DMA setting on c3

examples/storage/sd_card/sdspi/main/sd_card_example_main.c

@@ -34,8 +34,10 @@ static const char *TAG = "example";
 
 #endif //CONFIG_IDF_TARGET_ESP32 || CONFIG_IDF_TARGET_ESP32S2
 
-#if CONFIG_IDF_TARGET_ESP32S2 ||CONFIG_IDF_TARGET_ESP32C3
+#if CONFIG_IDF_TARGET_ESP32S2
 #define SPI_DMA_CHAN    host.slot
+#elif CONFIG_IDF_TARGET_ESP32C3
+#define SPI_DMA_CHAN    SPI_DMA_CH_AUTO
 #else
 #define SPI_DMA_CHAN    1
 #endif