This generates the "rd.gz" and "hddapp.tgz" that doesn't contain
anything of the sort but rather the OpenWRT rootfs. It works the
same way as how we generate the same layout for the NAS4220b.
For some reason the ImageInfo file is different for the SQ201.
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
