fdc: Move qdev properties to FloppyDrive

This makes the FloppyDrive qdev object actually useful: Now that it has
all properties that don't belong to the controller, you can actually
use '-device floppy' and get a working result.

Command line semantics is consistent with CD-ROM drives: By default you
get a single empty floppy drive. You can override it with -drive and
using the same index, but if you use -drive to add a floppy to a
different index, you get both of them. However, as soon as you use any
'-device floppy', even to a different slot, the default drive is
disabled.

Using '-device floppy' without specifying the unit will choose the first
free slot on the controller.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Message-id: 1477386868-21826-4-git-send-email-kwolf@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>