use correct lxc-init path in sshd template

lxc-init got moved into SBINDIR/init.lxc recently.
This broke sshd template because path wasn't updated there.
This patch should fix this issue.

Signed-off-by: Nikolay Martynov <mar.kolya@gmail.com>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>