unattended-file: Fix name of floppy device
unattended-file: Fix name of floppy device

Floppy device appears as 'fd0', not 'fd' on Linux. This fixes booting of
Linux systems against 'floppy' script injection method. Currently there
are none but Fedora's install script supports that if Boxes would choose
to use that method instead of 'hard disk'.

vbenes/gnome-boxes,vbenes/gnome-boxes