An incorrect quoting introduced in bf39edb3 caused a /{lib,etc} folder to
appear in Debian templates

The very next line :
    mkdir -p "${rootfs}/etc/systemd/system/getty.target.wants

makes creating ${rootfs}/etc/systemd/system/ unnecessary in the first
place
Signed-off-by: Maxime Besson <maxime.besson@smile.fr>