systemd: fix ordering for machineid and run-postinsts services

systemd: fix ordering for machineid and run-postinsts services

The remount-rootfs.service unit has been renamed to
systemd-remount-fs.service in systemd v183 and later.

The run-postinsts script writes to /var/log (a symbolic link to
/var/volatile/log), so systemd-tmpfiles-setup.service is added to After=
in run-postinsts.service to ensure /var/volatile/log is created before
running the script.

[YOCTO #4490]

(From OE-Core rev: 8b59ec4eb761d88445da94bb90aa2c5db0bbf365)

Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Saul Wold <sgw@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>