fusee: work around some dual-init SDMMC issues

fusee/fusee-primary/src/lib/fatfs/diskio.c

@@ -15,6 +15,13 @@
 
 static bool g_ahb_redirect_enabled = false;
 
+// Only use voltage switching in stage2 and later.
+#ifdef FUSEE_STAGE1_SRC
+#define MMC_VOLTAGE_SWITCHING_ALLOWED false
+#else
+#define MMC_VOLTAGE_SWITCHING_ALLOWED true
+#endif
+
 /* Global sd struct. */
 static struct mmc g_sd_mmc = {0};
 static bool g_sd_initialized = false;
@@ -26,7 +33,7 @@ int initialize_sd_mmc(void) {
 	}
 
 	if (!g_sd_initialized) {
-		int rc = sdmmc_init(&g_sd_mmc, SWITCH_MICROSD);
+		int rc = sdmmc_init(&g_sd_mmc, SWITCH_MICROSD, MMC_VOLTAGE_SWITCHING_ALLOWED);
 		if (rc == 0) {
 			g_sd_initialized = true;
 			return 0;