unify: xyz_load_dtb -> loadftd: mk_mmc.sh/setup_sdcard.sh

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
unify: add boot_classic/boot_ftd to make it easier to switch: mk_mmc.sh/setup_sdcard.sh

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>