Refactor some names

Additionally:
- Do not retry to init sd if all modes failed in Nyx.
- Do not try to read/write if sdmmc controller and card are not initialized.

bdk/storage/sdmmc.h

@@ -116,6 +116,7 @@ typedef struct _sdmmc_storage_t
 	mmc_ext_csd_t ext_csd;
 	sd_scr_t      scr;
 	sd_ssr_t      ssr;
+	int initialized;
 } sdmmc_storage_t;
 
 int sdmmc_storage_end(sdmmc_storage_t *storage);