Add diagnostics to preinit
Add alternative init-debug

We don't have the usb0 network interface on hammerhead and looks like it
happens on SailfishOS too.

This causes the default init-debug script from the droid-hal package to
reboot the device, thus preventing the boot.

With this script we remove the reboot. While we are here we also enable
a telnetd on the 2323 port to probe the device when things go wrong.
Of course, telnet will not be running on a finished product.