sdmmc v2: Add full SD card fallback initialization

hekate main always runs in compatibility mode (SDR82).
This ensures speed on boot process.

Nyx will first try SDR104.
If the sd card is a sandisk U1 and fails, it will try the compatibility mode.
After that it fallbacks to lower bus speeds.

Both support 1bit mode for broken sd card readers.

Having the new error checking in the sdmmc driver, allows for all that to work.
It can now fail instead of continuing, like how HOS reacts.

bootloader/storage/nx_sd.h

@@ -22,10 +22,21 @@
 #include "sdmmc_driver.h"
 #include "../libs/fatfs/ff.h"
 
+enum
+{
+	SD_INIT_FAIL  = 0,
+	SD_1BIT_HS25  = 1,
+	SD_4BIT_HS25  = 2,
+	SD_UHS_SDR82  = 3,
+};
+
 sdmmc_t sd_sdmmc;
 sdmmc_storage_t sd_storage;
 FATFS sd_fs;
 
+u32  sd_mode_get();
+int  sd_init_retry(bool power_cycle);
+bool sd_initialize(bool power_cycle);
 bool sd_mount();
 void sd_unmount();
 void *sd_file_read(const char *path, u32 *fsize);