use symlinks to install systemd services to let dh_installsystemd choose whether to install into /lib or into /usr/lib

stop installing /usr/lib/systemd/system-shutdown/reform-poweroff now that the reform-lpc module does the right thing

stop installing /usr/share/u-boot-menu/conf.d/reform.conf as it does not allow for platform specific settings -- use /etc/default/u-boot instead

Otherwise, an inserted SD card will look for a partition with the
reformsdboot and reformsdroot label, find it on the emmc and use those
instead of sd-card.

reform-check: check for old /etc/flash-kernel/preboot.d/00reform2_preboot overwriting /usr/share/flash-kernel/preboot.d/00reform2_preboot