fdc: Add a floppy qbus

This adds a qbus to the floppy controller that should contain the floppy
drives eventually. At the moment it just exists and is empty.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1477386868-21826-2-git-send-email-kwolf@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>