With the wifi fixes that involed deferring mmc0, the host indexes reordered causing sd/emmc to go missing.  This forces the mmcblk0/mmcblk1/mmcblk2 to look for the device name which inclues the register offset.  Names will be consistent now regardless of card or controller enumeration.  It would be preferred to use device tree aliases to indicate this, but they don't currently exist for the mmc framework.