udev-extraconf: Use the canonical file name of systemd
The new version of systemd has changed the symbolic link between
/sbin/init and /lib/systemd/systemd to relative. So the output of
the command 'readlink /sbin/init' become:
../lib/systemd/systemd
Then it causes the following check of "/lib/systemd/systemd" to return
false. Fix this issue by using the canonical file name of the systemd.
Signed-off-by: Kevin Hao <kexin.hao@windriver.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
