lxc-debian.in: Fixed errors if dbus is not installed

lxc-debian.in: Fixed errors if dbus is not installed

The lxc-debian template debootstraps a minimum debian system which does not contain dbus.
If systemd is used this will result in getty-static.service to be used instead of getty@ .
The systemd default files uses 6 tty's instead of the 4 the script creates.
This will lead to repeated error messages in the systemd journal.

Signed-off-by: Cyril Bitterich <Cyril.Bitterich@1und1.de>
Acked-by: Stéphane Graber <stgraber@ubuntu.com>