- revert inverting fstype and fstype2:
    * in either before or after this patch, formatting will be forced to one of the specified fstypes whenever we set fstype2=valid_type. People that want ext4 formatting, won't be happy after previous patch
    * as suggested by mdmower, revert to original cwm way inverting fstypes and always set fstype2=auto in device tree
    * this will force rm -rf on device instead of a true formatting in a forced fstype
    * however, you need now to format sdcard outside recovery as all it will do is rm -rf on it
- since fstype2=auto in device tree, exFAT patch should be no more needed if we always set fstype=auto in device tree
  mount will be always done through system with auto in /etc/fstab file set by write_fstab_root()