Support for booting from eMMC

Fusee will Look for FAT32 partition on BOOT1 (1MB offset), BOOT1, GPP, SD, in this order
If a .no_boot_storage file is found in the root directory, the partition is skipped

fusee/program/source/fatfs/fusee_diskio.cpp

@@ -33,4 +33,13 @@ bool diskio_read_system(void *dst, size_t size, size_t sector_index, size_t sect
 bool diskio_write_system(size_t sector_index, size_t sector_count, const void *src, size_t size) {
     /* Don't allow writes to eMMC GPP partition */
     return false;
+}
+
+bool diskio_read_boot1(void *dst, size_t size, size_t sector_index, size_t sector_count) {
+    return R_SUCCEEDED(::ams::nxboot::ReadMmc(dst, size, ::ams::sdmmc::MmcPartition::MmcPartition_BootPartition2, sector_index, sector_count));
+}
+
+bool diskio_write_boot1(size_t sector_index, size_t sector_count, const void *src, size_t size) {
+    /* Don't allow writes to eMMC BOOT1 */
+    return false;
 }