env_load() chaing for FAT/MMC source

mmc_start_init()               // "MMC: no card present"
mmc_init()
mmc_get_dev()                  // from .get_dev = ...
get_desc()                     // calls drv->get_dev
blk_get_devnum_by_typename()
get_dev_hwpart()
blk_get_device_by_str()        // "** Bad device mmc 0 **" (removed now)
blk_get_device_part_str()
env_fat_load()
env_load()                     // "Failed (-5)" (removed now)