Rename sd_utils to fs_utils, etc

Redesign fs_dev, raw_dev, introducing device_partition and switch_fs. ...

In theory, one could mount an encrypted FAT partition itself coming from a disk image, etc.

[stage1] refactor diskio.c

stage1 -> stage2 again

[stage1] unstub multiple sector-r/w code

fusee: undo a silly mistake in longer-than-8K operations

Merge pull request #93 from encounter/fix/stage2-args ...

Fix stage2_args_t mismatch

Move sd init into diskio.c, write code for latest commit

fusee: allow sdmmc_read / sdmmc_write of more data than fits in the bounce buffer

fusee: actually obey the SD spec when switching voltage

fusee: support low-voltage SDMMC mode

fusee: use full bus width and faster initial clock speed

[sdmmc] sdmmc_handle_cpu_transfer: handle unaligned buffers

Fix struct tegra_sdmmc definition ...

Definition errors were cancelling each other (for the most part)

[sdmmc] Fix const-correctness issue

stage2: fix init malloc size for stage2_args_t

Fix stage2_args_t mismatch

Refactor stage1's and stage2's main.c files

Fix bug in crt0

Make di.c accept arbitrary FB addresses, fix flickering issues

Fix faulty IRAM check in check_32bit_address_range_in_program

Fix inverted condition issue in check_32bit_address_range_loadable

[stage1] Fix DEFAULT_BCT0_FOR_DEBUG

Rewrote crt0, init, and chainloading code ...

start.s, init.c, linker.ld and linker.specs are meant
to be re-used by user applications, should they remove the defines
from init.c and the .chainloader* sections from the linker script

fusee: fix boot partition selection

fusee: fix regression in card detection

Upgrade FatFs to R0.13b

Don't pass the mmc struct around

Fix const-correctness issue in sdmmc.h

Normalize drivers between stage1 and 2